By this time Algernon was at the door, poking his paws into the narrow gap beneath it and gnawing at the wood with his teeth. When Tess reached down to pick him up, he jumped in fright, as though he had been taken by surprise. He had never done that before, either. He wriggled and squirmed as she pushed him through the small door of the cage, and threw himself against it when she closed it. Tess hoped it was the loss of the wheel that had upset him, and that once he found it back in its place he would settle himself down. His behaviour disturbed her more than she liked to admit, and she wondered if she should take him to the vet.

'White rat in pain, huh?' she said to him. 'White rat afraid of sore head? Sore belly?'

Algernon paused in his restless scurrying and looked at her. 'White rat go,' he said, his thought images dim and poorly formed. 'White rat go under city.'

His pictures of the rats' underground system were whimsy, like a young child's drawing of a fairy-tale land. But it was the first time he had used that image, or even given any intimation that he knew such a place existed.

'Brown rats in tunnels,' said Tess. 'Brown rats tough, fierce, biting white rat.'

'White rat go,' said Algernon stubbornly, his restlessness returning. 'White rat go, white rat go, white rat go.' He began to chew with his yellow teeth at the bars of the cage.

Tess sighed. 'Teeth worn down,' she said to him. 'Sunflower seeds won't open, white rat hungry.'

Algernon took no notice whatsoever. Tess returned to the window, but it was impossible for her to relax with the sound of Algernon chewing and scratching and rushing around his cage. Eventually she picked up a book and went downstairs, hoping that he would settle down in her absence. If he was still the same way tomorrow she could bring him to the vet.

Her parents were glad to see her coming down, and her father made room for her on the sofa beside him.

'Everything all right?' he said.

'Just Algernon. He's a bit restless. It's not like him.'

'I expect he needs a pal,' said her mother. 'What about getting another one?'

'As long as it's not female,' said her father. 'There's enough rats in the world as it is without breeding more of them.'

Tess laughed, rea.s.sured. The TV programme was humorous, the room was warm, and she had no premonition at all of the dramatic changes that were about to come into her life.

When the evening film was over, Tess brought an apple upstairs to share with Algernon as a bed-time treat. The rat however, had other things on his mind. The room was cold when Tess came into it, and the first thing she did was to go across and close the window. There was no sign of the phoenix beyond it, and she turned her attention to Algernon. He was upside down, hanging by his paws to the wire roof and gnawing on the metal clasp which kept the roof hatch secure. The water bowl had been knocked over again, and almost the entire contents of the cage had been hurled through the bars, littering up the room in a wide circle around the cage. Tess groaned and fought down a desire to punish the white rat. He was already disturbed enough, and scaring him further would not accomplish anything. Far better to try and find out what the problem was.

'Apple, huh?' she said.

In reply, Algernon dropped from the top of the cage, twisting in mid-air so that he landed on his feet, then proceeded to perform the most extraordinary feat of rodent gymnastics, leaping up the sides of the cage, across the roof and down to the floor again in a dizzying sequence of somersaults.

'White rat go, white rat go, white rat go,' he repeated as he swung wildly around.

Tess began to realise that the situation was much more serious than she had thought. It was clear now that the problem wasn't just going to disappear and there was no sense in trying to ignore it. Where did Algernon want to go, and why? She turned his repet.i.tive visual statement into a question and, in reply, Algernon sent a most extraordinary image into her mind.

It was a little like the visual name the city rats had given to Kevin, a gruesome mixture of rat and a rat's conception of a boy. But this new image was vaguer, and tied up with other images as well; wolves perhaps, and bats, all in darkness. Strangest thing of all, and the most disturbing thing to Tess's human mind, was that this being was calling. It was calling for all the rats in the city to come towards it, and the reason for Algernon's behaviour was suddenly crystal clear. For Tess could tell without any doubt that if she had been a rat at that moment, she would have had no resistance whatsoever to that call.

CHAPTER THREE.

TESS SAT ON THE windowsill and stared out into the darkness, longing for the phoenix to come. Behind her, Algernon was still raiding against the sides of his cage, his anxiety growing into a kind of dementia as he found that all his efforts were useless. Tess kept her mind firmly closed to his pathetic babbling. The weird communication that she had tuned into with her rat mind disturbed her a great deal and she knew that she was turning her back on the problem. But the lure of the phoenix was too strong.

Her parents' door eventually closed, and in a surprisingly short time she heard her father's regular snores coming through the wall. There was still no sign of the golden creature, but as she looked out into the darkness, Tess realised that this didn't matter. She could still re-live the experience on her own. The wonder of being a phoenix had nothing to do with companionship. It was beyond companionship; beyond all worldly attachments.

She was just on the point of deciding to Switch when something happened which made her change her mind. In a last, desperate attempt to break free, Algernon hurled himself at the door of the cage with such force that it sprang open and he found himself sliding over the edge of the chest of drawers and falling towards the floor. Tess caught sight of him as he fell, but before she could get to him he had landed, picked himself up, and was racing towards the corner of the room.

Tess followed, irritated by the delay but concerned as well. Despite Algernon's limitations as a companion, she was fond of him and she would have hated to see him coming to any harm.

There was no fireplace in Tess's room but there had been one, long ago, and the chimney-breast ran up one wall. Beside it was a redundant corner, about the size of a wardrobe, and Tess had helped her father to put doors across it when they first moved in. She kept her clothes there, hanging from an old broom handle, and beneath them her shoes and boots were arranged on the floor.

Algernon ran straight towards this cupboard as though he knew exactly where he was going. Tess and her father had never got around to fixing bolts on to the doors, and they always stood slightly open. Algernon nosed through the gap and disappeared among the footwear. Tess followed and pulled the doors wide open, just in time to see the rat's pink tail disappearing down a tiny gap between the floorboards and the wall of the chimney-breast. There was only one way to follow him. Switching had become so much a part of Tess's nature that she no longer had to think about it. She didn't even stand still but, in one fluid movement, changed into a brown rat and went slithering down the hole in hot pursuit.

Beneath the floor and behind the walls, a maze of old rat pa.s.sage-ways ran through the house. Tess hadn't known they were there, but she might have guessed. All old houses are riddled with rat-runs, even if they aren't in current use.

Despite Tess's speed, Algernon had already disappeared behind the first of the joists which ran beneath the floorboards. But to her surprise, Tess realised that she didn't need to follow him. Her rat mind had picked up on the command from the mysterious stranger, and there was no doubt that she and Algernon were heading in the same direction.

She scuttled down through the walls of the house, between the courses of bricks, until she came into a long, rat-made conduit which connected with the drains. At the end of that, she caught a glimpse of Algernon's tail as he turned a bend in a pipe. She accelerated, and after a few more twists and turns she found that she was gaining on him. Before long she had caught up, but when she tried to communicate with him, he ignored her, his mind fixed exclusively on the unknown destination ahead.

The most direct way of following the call led the two rats across the city by way of drains and under-floor pa.s.sages. Tess was surprised by Algernon's speed and agility, and also by his apparent lack of fear. She realised as she ran beside him that this was what he had been deprived of as he grew up in his artificial environment. It was no surprise that he was dull-witted and inarticulate, since he had missed out on the rats' basic education in life. But all that was changing now. Who could tell how much his intelligence might increase, provided he could avoid the common pitfalls of city rats and stay alive long enough to learn his way around.

One of these hazards, poison, was very much in evidence in several of the gardens they had to pa.s.s through. Tess was on guard, but Algernon was far too preoccupied to be diverted by food, no matter how enticing it smelled. Where cats were concerned, however, his single-mindedness was a considerable handicap and, on two separate occasions, Tess had to rescue him; once by steering him away from the waiting jaws of a large tom, and once by charging a cat that was just about to grab him from behind. The cat was so surprised by Tess's aggression that she turned tail and fled, and by the time she had recovered herself, the two rats were long gone.

The rest of the journey was safer. When they joined the sewers, Algernon proved to be an excellent swimmer, and his regular exercise on the wheel had made him fit enough to cope with the slippery exertions of climbing back out of them. By the time they surfaced, in order to cross a small open square, he was a lot less white than he had been, but still not as camouflaged as Tess would have liked him to be. Because what she feared most for him had yet to be encountered, and that was the reaction of the other rats. She was not surprised that they hadn't come across any before now, because she was working on the a.s.sumption that all the others within range of the strange call had got a long head start on them. They were stragglers, she and Algernon, bringing up the rear. But she knew that before long they would be getting close to their destination, close to the moment of truth.

They dropped back into the underworld by means of a hole in the ground beneath the cover of bushes in a corner of the tiny park. Tess called to Algernon again, warning him to take his time and watch out for cats, but when she opened her mind for his reply she caught nothing but a babble of rat images. They were close. Above them, they could hear the deep rumble of a car pa.s.sing along a street. A moment later they were on the other side and, surprisingly, beginning to climb.

Abruptly, Algernon stopped. He was ahead of Tess and blocking the narrow pa.s.sage which ran higgledy piggledy through a foundation wall between detached houses. She couldn't see beyond him, but she could hear the restless rustling of a great gathering of rats. Impatiently, Tess squeezed her way in beside Algernon, whose fluid body seemed to elongate as he made room for her in the narrow s.p.a.ce. They were looking into the kitchen of a vacant house. Tess held her breath, astonished by what she was seeing. There were rats of all shapes and sizes: rats with grey coats, brown coats, black coats, sleek rats and mangy rats, thin rats and fat ones, all milling around in an aimless fashion. The dim light on their moving backs made Tess think of water, rippling and flowing. The kitchen was flooded with rats.

Her first concern was for Algernon. The hole in the wall where they were standing was about two feet from the ground. It would be easy to slip down the wall on to the floor, but not so easy to climb back up if there was trouble down there. A rat could scale that height in a flash, but not without a run-up. Already a few twitching noses were beginning to turn and look with curiosity at the two newcomers. Tess tried to pick up on the reactions, but the images she received were the visual equivalent of a roar in a football stadium-it was impossible to pick out any individual communication. She scanned the crowd, hoping to find someone she knew, but there was no one she recognised. She hesitated, and beside her Algernon was hesitating too. Whatever certainty had brought him here was severely weakened by the sight of so many rough and street-wise relatives.

Their decision was made for them. Without warning, another group of latecomers arrived in the pa.s.sage behind them and, in their urgency to obey the call, they crowded forward relentlessly, pushing Tess and Algernon out of the hole in the wall and down into the restless mob below. Tess scrabbled through the crowd, desperate to stay close to Algernon and defend him against attack, but to her relief it proved unnecessary. The other rats grudgingly made s.p.a.ce for him on the floor. Those closest to him inspected him curiously, but none had time or energy for aggression. All minds were firmly fixed on the powerful call that had brought them together.

Tess tuned into it as accurately as she could. It was a strange feeling, being drawn to something she could neither see nor hear, but which exerted such a powerful attraction on the rat part of her mind. It wasn't an active call; none of the rats was being asked to do anything except be there. It was as though they had been drawn by some sort of magnetism and were now held within its field of force, powerless to move away.

When she looked round, Tess saw Algernon struggling across the backs of the other rats towards the opposite side of the room. She tried to call him, aware that walking on another rat's back without permission is extremely bad manners. But if he heard her at all, he ignored her and carried on, oblivious to the warning clouts and nips that the other rats were giving him. Tess bared her teeth in exasperation and followed. There is no equivalent of an apology in the rat language; instead, Tess tried to convey a sense of urgency to the rats whose backs she crossed. It was of little use, however, since all but the eldest and wisest rats in the gathering were feeling a similar sense of urgency and had little patience with shovers. By the time Tess caught up with Algernon on the other side of the room, she was covered in little cuts and bruises and thoroughly fed up.

Algernon was scratched and bitten too, but he didn't seem to care. He was wriggling into a small hole that had been chewed in the bottom of the door which led into the hall. Tess followed. This narrow s.p.a.ce was full of limp cardboard boxes and dusty trunks, long since abandoned. Rats were packed into every available s.p.a.ce, level upon level of them, like the audience at a mega pop concert. A flight of stairs ran down from the floor above, and Tess noticed something which filled her rat mind with wry amus.e.m.e.nt. On the top step a cat was sitting, its face turned away in silent uninterest, as though it had no idea that it was surrounded by its worst enemy. Tess knew that the nonchalance was feigned, that beneath its smug exterior that cat was absolutely terrified. It was another measure of the single-mindedness of the gathered rats that they didn't set upon the poor creature and tear it to shreds. Despite herself, Tess hoped that they wouldn't change their minds.

Ahead of her, Algernon was slithering through the gathering again, over and under and around, any way that he could see of getting across the room. Tess followed, steeling herself against another series of bites and blows. From time to time she looked around her, hoping to catch a glimpse of friends from the past; Long Nose, perhaps, or Stuck Six Days in a Gutter Pipe, but she had no luck. They could have been anywhere. There was no way for Tess to tell how many rats had gathered, or if any were exempt from the call.

Algernon scuttled along beside the wall and Tess followed, determined to try and hold him still by force if once she managed to catch up with him. But as they slipped through the open door into the front room, a new message began on the stranger's mental wavelength. It was electrifying. Every rat in the place sprang to attention, some sitting up on their tails or standing on their hind legs in an effort to understand.

Tess was no less attentive than the others. The images coming into her mind were quite clear. The rats were to search beneath the city for a certain type of large, stone container. Some of these structures would be open to the human world, in huge bas.e.m.e.nt rooms where they were regularly visited. Others would be buried in the ground where no humans could reach, and these were the kind that the rats had to go and find. If and when they succeeded they were to return and report.

That was all. As abruptly as it had started, the communication ended, and for a moment there was a profound silence. Then the visual babble began again, becoming pandemonium as a hundred thousand rats began to react. Tess resisted the temptation to join the confusion and looked round. Rats were pouring out of the room as though someone had let the plug out. She caught a glimpse of Algernon disappearing into a hole, like a piece of white paper being swept by the current into a drain, and a moment later she was alone.

CHAPTER FOUR.

ABOUT A MILE AWAY, Jeff Maloney, the head keeper of Dublin Zoo, was being woken from a deep sleep by the phone. His irritation at being disturbed was worsened by the fact that he had only just got to sleep, following a long evening trying, unsuccessfully, to save a new-born calf in the pet section. Even now it was the first thought that came to his mind. The irony of it. The zoo had successfully bred hippos, elephants and rhinos, but when it came to a common Jersey cow, they had been powerless to save the calf. As he crossed the sitting room, Jeff tripped over a dog first, and then a chair. He was swearing by the time he reached the light-switch, but it was nothing compared to the torrent of abuse that he let loose when the phone stopped ringing the instant before he reached it.

Tess stood in the middle of the floor and tried to gather her thoughts. She sent out a few half-hearted calls towards Algernon and her other rat friends, but if any rat picked them up he or she was far too preoccupied to respond. It was all so confusing, and Tess's rat mind hadn't much s.p.a.ce for rational thought. For a few moments she scuttled around the empty house with the vague idea of finding something to eat in order to calm her nerves. At the top of the stairs, the cat was still frozen in the same position, even though all the other rats were gone. Tess knew that the poor creature would climb walls rather than go in there again.

Think; she needed to think. Slipping back into the third of the rooms, she Switched back into human form. The smell of rats was strong, even to a human being's weak sense of smell. Tess wondered how she would feel if she opened the door one day and found her own house as full of rats as this one had been. Her parents would call in pest control; the house would be evacuated-perhaps the whole street. But no matter how hard people tried, they would never get rid of the rats in the city. There would still be rats there long after the human race had died out or moved elsewhere.

Tess shivered. She was still wearing her school uniform, but without a cardigan or a jacket. She was wasting time. As soon as she put her human mind to the problem which faced her she began to see her way forward. The image of the person that had called was still confused, but of two things she was sure. He was a boy, and he was a Switcher. The realisation brought a sense of excitement with it, because Kevin had told her that all Switchers must meet with another to pa.s.s on their knowledge. She had often wondered since whether this was true and, if so, when she would encounter this new friend. Now it seemed that the time had come. The only problem was that she still had to find him.

She concentrated hard, trying to remember how it had felt to her as a rat when the message had come through so strongly. Where, exactly, had it come from? Somewhere above, she realised, and behind her as she stood now. She turned round. Yes, that way. Not directly above, but ahead of her now; a house across the street perhaps?

Jeff Maloney was just getting comfortable in bed when the phone rang again. For a few seconds he hesitated, then decided not to ignore it. He took a different route across the sitting room this time, but unfortunately the dog had also decided to change location, and once again there was an outraged yelp as Jeff's foot came into contact.

This time he went straight for the phone, fumbling in the darkness for the receiver.

'h.e.l.lo?'

'h.e.l.lo. Jeff Maloney?'

'Speaking.'

'Garda barracks here. We have a report of an unusual bird at the edge of the Phoenix Park. We were wondering whether you had lost any.'

Jeff had visions of blundering around with nets in the night. It wouldn't be the first time such a thing had happened. 'What sort of bird?'

'I'll hand you over to the witness, hold on.'

There was a crackle, and then a sort of knocking sound, as though the receiver at the other end had been dropped on the floor. At last a rather drunken voice came on to the line.

'h.e.l.lo?'

'h.e.l.lo.'

'h.e.l.lo?'

'h.e.l.lo. Jeff Maloney here. You've seen an unusual bird?'

'By G.o.d, I have. Never saw anything like it. It must be one of your lads, come out of the zoo. I never saw anything like it.'

'Can you describe it to me?'

'It was golden, pure golden. I never saw anything like it.'

Jeff gritted his teeth, convinced that he was dealing with a hallucination. It wouldn't have been the first time that had happened, either. 'Can you tell me any more?' he said.

'I've never seen anything like it. It had ... sort of ... long tail feathers, hanging down. And it was golden.'

'Probably a hen pheasant,' said Jeff. 'We quite often see them in the park at this time of year. Was it sitting in a tree?'

'It was, by G.o.d, but it wasn't a pheasant, no way. It was golden, pure golden, I've never seen anything like it.'

Jeff sighed. 'A trick of the light, I'd imagine,' he said, as kindly as he could. 'Those street lights can have a strange effect sometimes.'

'Well, you can say what you like,' said the voice on the other end of the line, 'but that was no pheasant, hen or c.o.c.k. I've-'

'-never seen anything like it, I know,' said Jeff, his patience finally deserting him. 'I appreciate your calling, and I'll check it out first thing in the morning on my way to work.'

'It'll be your loss if it's gone by then,' said the voice.

'It'll be my loss if I don't get a bit of sleep tonight, too. Goodnight, and thank you for your information.'

As he put down the receiver, Jeff heard the dog shuffling into the corner, well out of range.

The best way for Tess to get out of the empty house was to become a rat again. She made her way out by using a series of pa.s.sages and air vents, then checked carefully up and down before leaving cover.

The street meant nothing to her. It was like dozens of others in the area, made up of two-storey brick-built houses dating from the fifties and early sixties. For some reason, she had thought that she would recognise the house where the Switcher was living as soon as she saw it, but now that she was out in the open, one house looked pretty much like the next.

A car came slowly down the street and Tess instinctively slipped into the damp and oily gutter, sheltering behind the wheel of a parked van until the coast was clear. When she came out from behind the wheel, it was in the shape of a small mongrel dog. She had often used this form when a certain type of investigation was needed.

It was no use, though. She patrolled the length of the street in both directions, catching every available scent from the sleeping households, but there was nothing out of the ordinary. She had hoped for some lingering residue of the Switcher's ability, a variety of animal smells coming from one of the houses perhaps, or one of an unusual nature. But apart from the still pervasive smell of rats, there was nothing out of the ordinary at all. The dog's nose couldn't help.

She craned her neck to look at the upstairs windows. Presumably, whoever had called the rats was still awake, which probably meant a light on somewhere. But the only lighted windows were in a house at the end of the street, and the voices which could be heard coming from it were of people much older than Switchers could be.

Tess considered changing into something smaller and taking a look around the inside of a few of the houses, but her instinct told her it was beginning to get late. She remembered the phoenix with longing, and became aware of the time she was wasting by trotting up and down the empty street. There would be other nights for investigating; all she needed to do was to find out where she was and she could come back any time. So she trotted along until she found the sign on the wall which told her the name of the street. To her dog mind it meant nothing, just a white square with bits of black stuck on it, like the bits of cars which were at her eye level and which had to be avoided if they were moving.

Tess looked along the street. There was no sign of anyone around but she still felt too exposed to Switch. The nearby houses had tiny front gardens with low walls; no cover at all. The best place she could find was the pavement between a transit van and the windowless corner wall of the end house. She slipped in there and sat down close to the kerb. Then, with a last glance around her, she Switched. She waited for a minute or two, then got up and strolled back to look at the street-name. There was still no sign of anyone awake. She had been lucky.

Back in bed once again, Jeff Maloney found that he couldn't sleep. He lay on his back first, then each side in turn, and finally on his stomach, but he just couldn't get comfortable. He thought about his last girlfriend and about his next one, whom he hadn't yet met but who would be perfect in every way when he did. He thought about what he would do on his day off, and what he would do in his summer holidays, but nothing worked. Every time he got comfortably absorbed in his thoughts, the slightly slurred voice returned to his mind: 'It'll be your loss if it's gone by then.'

Eventually, with a sigh of exasperation, he threw back the covers and sat up on the edge of the bed. 'I should have been an accountant,' he said to himself.

It was as well that Tess, in the shape of a pigeon, was able to cross the city faster than Jeff Maloney could cross the park. At the time he was visiting the barracks and getting the exact location of the alleged sighting, Tess was joining the three-toed phoenix on the branch of the tree outside her window. But the distant glimpse that the zoo-keeper got of two flecks of gold rising into the night sky was enough to rouse his curiosity.

CHAPTER FIVE.

THE FOLLOWING MORNING, WHEN Tess's father went into her room to wake her, he found her bed empty. As he looked round, his heart filled with anxiety, he noticed that Algernon's cage was empty too.