The Doctor shook his head. 'A sample of Johan's blood. Couldn't use the TARDIS lab to test it, obviously.'

Fitz thought of Johan, pale and drained-looking in his hospital bed. 'So, there's no way of telling if he's carrying an alien virus?'

The Doctor shook his head. 'No.'

'We'd better get back in there then, keep an eye on him.' Fitz stood up, but the Doctor remained seated. Where was his sense of urgency? 'Doctor?'

The Doctor stood up, clapping his hands together. He looked over at the hospital, a worried expression on his face, as if he were steeling himself for something. 'You're right. Mustn't let the situation get out of hand.'

They started walking towards the hospital, the Doctor talking quickly, seeming to have recovered some of his verve. 'Tell me about that creature you found in the forest.'

Fitz recalled the image of the thing, its spiderlike legs and deflated, hourgla.s.s-shaped body. He described it for the Doctor. 'What do you think it is?'

The Doctor shrugged. 'No idea. From what you say it sounds like a creature used to lower gravity, which ties in with the creature from the farm and that insect we saw in the forest. That wasn't used to Earth's gravity at all that's why it couldn't fly properly.'

'That's three types of alien creature we've seen today, Doctor.'

'All within a fairly localised area,' said the Doctor as they went through the revolving door into the hospital lobby. 'Interesting.'

'So where are they coming from?' said Fitz.

The Doctor quickened his pace. 'From where Sam's gone, from where Johan has been.' He was almost running now, along the wide grey-tiled floor towards the wing containing the isolation ward.

'Hang on,' said Fitz. He hadn't told the Doctor about the strange white-suited figures from the State Biohazard thingummy who had arrived to take the creature away. Oh well, time for that later, he supposed.

They found Kerstin standing in the grey-tiled corridor outside the isolation ward, her hands pressed on to the gla.s.s separating her from Johan. She didn't look up as they approached.

Fitz could plainly see that Johan was exactly the same as he had been before. Still and silent, like a corpse, the only movement the slow rising and falling of the crisp white sheets across his chest as he breathed.

'Kerstin,' said the Doctor, touching the girl lightly on her shoulder. 'How are you feeling?'

She looked up at him, her eyes damp with tears, which she brushed away. She smiled at the Doctor and said, 'I'm feeling as though I'm standing on the edge of a cliff, waiting to fall.'

The Doctor nodded sympathetically.

'It's the not knowing that's the worst part.' Kerstin's voice was flat, lifeless. 'Not knowing if he's going to be all right. I know the doctors seem to think he's physically OK but his brain could be mush, he could be a vegetable, he could never wake up.'

Fitz noticed that she seemed to trust the Doctor instantly, instinctively, and felt a shameful envy for the Doctor's ability to get on with anyone straight away. It had taken ages to break the ice with Kerstin; she'd seemed to realise he was a person only when he had told her about Sam. And even that had sent her back into herself, thinking about Johan.

Now she was talking to the Doctor as if she'd known him all her life. Fitz might as well not exist. What was it about the Doctor and blondes?

He was shushing her now, calming her. 'I can't tell you if he's going to be all right or not. I can't predict the future.' He glanced at Fitz as he said this. 'But Johan is in the best place.'

Fitz was looking at Johan as the Doctor spoke, wondering what he'd gone through. Where he'd been. If he'd seen Sam. And hang on, was that a movement? Fitz stepped closer to the gla.s.s. He was sure he had seen a movement, the white sheets stirring, as if Johan was trying to raise his hand.

The Doctor was still talking to Kerstin. They seemed to have forgotten he was there. He opened his mouth to speak but hang on, if he was wrong he'd only be raising Kerstin's hopes and then bringing them crashing back down again. He had to be sure. So he stood and watched Johan like a hawk, alert for any sign of movement. There definitely this time, the sheet tenting slightly just above where Johan's right hand would be. And then Johan rolled his head, his lips moving slackly.

'Doctor!' said Fitz. 'He's coming round!'

The Doctor and Kerstin were at his side in an instant, Kerstin's eyes and mouth wide, the Doctor's brow creased in a frown of concentration.

'Are you sure?' said the Doctor, obviously not trusting Fitz's powers of observation since he mistook Kerstin for Sam earlier that day.

Fitz sighed. 'Do bears sh'

'All right, you're sure,' said the Doctor quickly.

Then Johan opened his eyes, let out a low moan and tried to sit up. Then slumped back down again, his eyes wide and glistening, staring at the ceiling.

The Doctor opened the door to the isolation ward and hurried in, followed by Kerstin.

Where were the doctors? wondered Fitz, looking around. And the police? Had Nordenstam left anyone waiting in the room further down the corridor? He darted down to have a look. The room was empty, coffee cups on the table, a folded newspaper on a chair. Fitz realised belatedly that it was he, Fitz, whom Nordenstam was relying on. Should he call him? The mobile phone bulged uncomfortably in his trouser pocket. No. The last thing they wanted was the police b.u.mbling around, interfering.

With a mental apology to Nordenstam, Fitz went back to the isolation ward. The Doctor was kneeling by Johan's side, whispering his name into his ear. Kerstin knelt on the other side of the bed.

Fitz hovered in the door, not sure of what to do. He watched as the Doctor pa.s.sed his hand in front of Johan's blue eyes.

'He's not responding,' said the Doctor softly.

Kerstin hid her head in her hands and began to cry softly.

Then Johan spoke, his voice barely a whisper. 'Ker... Kerstin?' His eyes searched the ceiling, looking anywhere but at her.

'Johan,' said Kerstin, leaning over him. She spoke some words in Swedish, stroked his forehead.

On hearing her voice, Johan struggled to sit up, his voice rising in panic, babbling in Swedish Fitz wished he could understand.

The Doctor leaned over him, smoothing his hair. 'Johan, what can you see?'

Johan began panting, moaning and writhing from side to side. Fitz walked around the bed, held Kerstin back. Cruel as it looked, the Doctor had to question Johan.

'Things,' said Johan, in English responding to the Doctor. 'Horrible things. What are they? Where am I? Kerstin!'

His convulsions became too much for the Doctor and Fitz moved to help calm him down.

Then there was a voice from the doorway. 'What is going on here?'

Fitz turned to see Dr Lindgard bustling into the room, a nurse in tow.

'Please step away from the patient,' said Dr Lindgard calmly.

Johan was still thrashing around on the bed. Kerstin was holding his hand, trying to calm him.

The Doctor bent over Johan, muttering something into his ear and fishing in his waistcoat pocket. He drew out a silver pocket watch, and began swinging it before Johan's eyes.

Lindgard took a step nearer, firmly pushing Fitz out of the way. 'I said step away. The patient needs more sedative.'

'Stop calling him that!' yelled Kerstin, her face red and streaked with tears. 'His name's Johan. Got that?'

The Doctor was ignoring everyone, concentrating on Johan, swinging the watch back and forth. Incredibly, Johan was focusing on the silver object.

'This is ridiculous.' Lindgard's voice was still calm and even. 'What can he hope to achieve?' He motioned the nurse towards the bed. She was holding a small plastic syringe.

'It may be ridiculous,' said Fitz, holding the nurse back, 'but it's working. Look.'

Lindgard looked. Johan's convulsions had ceased and he was breathing normally. His eyelids had drooped closed, and he looked at peace once more.

Kerstin wiped away her tears and looked over at the Doctor. 'What did you do?'

The Doctor stood up, smiling from ear to ear and pocketing the watch. 'Simple hypnotic trance. He'll sleep peacefully for hours now.' He frowned as he caught sight of the nurse, hovering near the bed bearing her syringe. 'Far more beneficial than that muck. I'm afraid that's what may have caused his convulsions.'

'Nonsense,' snapped Lindgard.

Fitz could see that the Doctor was enjoying annoying the Swedish doctor.

'As a medical man, you'll agree that my methods, if not conventional, have had the desired effect.'

Lindgard drew himself up to his full height, and was about to say something when there was a scream from the other side of the bed.

They all turned to see Kerstin, struggling to get away from Johan, trying to prise his pale fingers away from her tanned brown forearm, where they held her in a vicelike grip. She looked terrified. Johan's eyes were still closed but his body was juddering, shivering, as though he were freezing to death.

'He's gone into reactive shock,' said Lindgard, glaring at the Doctor. 'The desired effect? I think not.'

Fitz dodged round the other side of the bed and tried to help Kerstin free herself. It was impossible.

'Doctor,' said Fitz, looking across the bed to where the Doctor and Lindgard stood. 'What's happening to him?'

The Doctor was shaking his head, his eyes wide. 'I don't know.'

Lindgard turned to the nurse and pointed to Johan. 'Sedative. Now!'

They shoved past the Doctor and rolled back the sheets. Fitz gasped. Johan's chest was simply swimming in sweat. It was running down his stomach and on to the sheets, where it spread out in a dark stain.

Ever professional, Lindgard didn't bat an eyelid at the sight. He held Johan's left arm while the nurse slid the needle into a prominent blue vein and depressed the plunger.

They both stood back, watching expectantly.

Fitz tried to prise Johan's fingers away again, but to no avail. They'd drawn blood, which ran over Kerstin's forearm to drip on the floor.

Kerstin's face was a knot of agony and Fitz could practically hear her gritting her teeth with the pain.

'It's not working,' yelled Fitz. 'It's not b.l.o.o.d.y working!'

The Doctor was staring down at Johan, his eyes wide, shaking his head.

What was wrong with him? He was usually so calm in a crisis, so confident, knowing exactly what to do. But he was just standing there.

Dr Lindgard ordered the nurse to get some morphine and she ran off, with a terrified stare at Johan's body. He was still shaking, bucking in the bed, his back arching, the perspiration dripping from him. Fitz's stomach lurched. It was pink. He was sweating blood.

Dr Lindgard was doing his best to hold him down, and even his calm facade was beginning to crack a little.

'Somebody help him,' cried Kerstin, her voice strangled with pain.

And then Fitz saw that a large bruise was forming on the flesh of Johan's stomach. A round, purplish blotch the size of a small plate. It was swelling, slowly, like a giant blood blister. A strange gurgling was coming from Johan's throat, and flecks of blood and spittle sprayed from his mouth.

'I think we should all get out of here,' said the Doctor.

Fitz had never been so angry with him. 'We can't leave Kerstin! What do you want me to do, cut his arm off?'

'That may be necessary,' said the Doctor, looking around as if for the most appropriate surgical instrument.

'Don't be ridiculous!' said Lindgard. His white coat was speckled with blood.

And then Johan sat bolt upright in bed, opened his eyes, let out a ragged scream, and flopped back down on the bed. At the same time he released Kerstin's arm and she staggered backwards, grimacing as blood flowed freely from her wound. Fitz ripped the sleeve from his shirt and used it to make a tourniquet.

'Look!' cried the Doctor.

Lindgard stood up, and backed away from the bed.

The purple blister on Johan's stomach was now the size of an upturned bowl. Suddenly, it split open, spraying them all with a clear, viscous fluid. Fitz dragged Kerstin away from the bed and back towards the door, glancing at Johan on the way.

What he saw would stay with him forever and he froze on the spot.

Long, black legs were forcing open the sides of the deflating blister, hauling out an orange hourgla.s.s-shaped body which quivered and pulsed with life. A smell hit Fitz's senses, the sickly smell of the thing in the forest.

'Everyone out of here!' yelled the Doctor.

His words shocked Fitz into action and he half dragged the hysterical Kerstin from the isolation ward. Dr Lindgard and the nurse followed, with the Doctor last, who slammed the door closed.

They all watched as the thing squatted on Johan's shattered body. Its black legs were glistening with blood, the hourgla.s.s-shaped body quivering, a ropelike grey tube emerging from it, as if tasting the air.

'Fascinating,' said Lindgard.

'What?' said Fitz, holding Kerstin's face against his chest. 'He's dead, you callous b.a.s.t.a.r.d!'

Lindgard turned to look at Fitz. His eyes betrayed no emotion. 'I've developed an air of detachment over the years.' He smiled, a prissy little expression which chilled Fitz to the bone.

Inside, another blister was forming, on Johan's chest. The first creature had dragged itself to the edge of the bed, leaving a trail of blood and entrails, and Fitz heard a wet slap as it flopped to the floor. The other blister burst open and another, similar creature emerged. Smaller versions of the thing in the forest.

The Doctor banged his fists together. 'I should have known something like this would happen! Something must have laid eggs in his gut, where they would have remained undetected.'

Fitz took his breath. It had all happened so quickly. Kerstin's face was blank, streaked with tears. Fitz shuddered. She was in deep shock. He was reminded of the looks on the faces of Charles Roley's test patients back home in London in 1963, at the time he first met the Doctor and Sam. The look on the face of his mother.

Dr Lindgard tried to usher them away from the isolation ward. 'I'm afraid I'm going to have to ask you all to leave.'

The Doctor shook his head. 'Impossible. We have to capture those things, a.n.a.lyse them.'