All round the first circle, doors began to open, and the alarm was briefly drowned out by the screams and howls of the damned. A green and purple demon with ape-like arms was unlucky enough to step out from the closest door.

"What's all the racket?" he demanded, before the tip of Zac's shoe came up sharply between his legs. The demon clutched his groin and dropped to his knees, then he toppled sideways, groaning, on to the floor.

More demons poured from more doors up ahead. Others still emerged from the rooms behind him. Zac looked down at the floors below and saw that they too, were brimming with monsters, all gesturing angrily in his direction.

With a flick of a switch, Zac primed the bomb and a three-second countdown began. He tossed the thing out over the frosted-glass barrier and into the big space in the centre of the rings. The bomb flipped twice, then began to fall.

It had barely travelled three or four metres downwards when the explosive charge detonated. The bottles ruptured, spraying a rain of holy water in all directions. Those demons unlucky enough to be hit by the spray began to scream as their hides sizzled and blistered.

"Wow," said Zac. "So that's what it does to them."

The din of the demons' screams echoed round the corridors of Hell. The spray had only hit a small percentage of them, but their thrashing and howling and begging for help had quickly plunged the whole place into chaos.

The demon he'd kicked was still lying on the ground, holding his crotch and trying not to vomit on the carpet. He gave a high-pitched whimper when Zac hauled him to his feet.

"The tenth circle. Can you take me there?"

The demon shook his head. Zac took one of the smaller water pistols from his waistband and jammed it in the demon's mouth. "Holy water," he explained. He cocked his head and listened to the screaming from the lower floors. "But then you probably guessed that. I'm going to ask you again. The tenth circle. Can you take me there?"

The demon shook his head again. Zac squeezed the trigger, just enough for a single drop of water to dribble into the monster's mouth. The demon's eyes went wide as his tongue began to sizzle and burn.

"Tenth circle," Zac urged. "Yes or no?"

"'Es!" the demon squeaked. "'Es!"

Zac glanced around the corridor. Those demons who hadn't been hit by the spray were shoving past the others, making their way around to him. They'd be on him at any moment.

"Then do it," he growled. "Now!"

There was a blip and Zac found himself standing in the room he'd been in earlier. There were the chains that had bound him and Angelo. There was the reclining chair. But it looked like a tornado had ripped through the place.

The chair was in pieces. The light that had been mounted above it lay smashed and broken on the floor. A gaping hole had been torn through one wall. From beyond it, Zac could hear shouts of anger and yelps of panic, and the roars of something monstrous.

The captive demon watched him, his eyes bulging, the gun still wedged in his mouth. Zac carefully removed the pistol. "Sorry about that," he said, then he drove a left hook across the demon's cheek, knocking him out cold. "And that."

He looked over to the hole in the wall. "Right, then," he announced to no one in particular. "I'm guessing this way."

Just as he reached the gap, something large and scaly came hurtling backwards through it. With a cry of pain, Haures smashed through a stainless-steel worktop and thudded hard against the wall. Black blood oozed from the duke's nose and mouth. He coughed violently, mumbled, "That's more like it," then slid sideways on to the floor.

Zac cautiously poked his head round the edge of the hole and peered into a room larger than the one he was in. It was filled with what was probably until very recently state-of-the-art medical equipment, but which was now little more than scrap metal bent into a variety of interesting shapes.

A large metal box, which may once have been a prison cell, stood in the centre of the room. One of its walls had been torn away, the others were scorched and black with soot. Sparks rained down from a broken electric light that hung from the high ceiling. The other lights flickered, more off than on.

Three of the demons in surgical masks chittered excitedly as they launched themselves into the shadows beneath the broken light. A bellow of rage rocked the room and two of the demons were hurled from the darkness at terrifying speed. Their spindly bodies went krik as they broke against the wall.

Zac looked on as the third little demon came darting out of the gloom, its eyes wide open with terror. It made it four steps before a hand reached out of the dark and swatted it to the floor. The demon screamed as the hand dragged it back into the shadows, and then the screams became muffled before abruptly coming to a stop.

Silence followed, broken only by a burp from the darkness.

Zac stepped through the hole in the wall. "Hey, Angelo," he said, doing what he could to control the shake in his voice. "Hoped I'd find you here."

Breath hissed in the shadows. A growl rumbled at the back of a throat.

"I came back. You know, to rescue you. Like I said. Because, well, I was thinking anda""

A jet of flame crackled towards him, forcing Zac to throw himself sideways. He rolled expertly and took cover behind the buckled remains of a metal wall. The flame had come from high up, somewhere near the domed ceiling itself. Zac raised his eyes. The ceiling was ten metres high, maybe more. Higher than Angelo's demon form had been. Much, much higher.

There was a clatter from the hole in the wall and Haures came staggering through. The Duke of Hell glowered gleefully up into the darkness and extended his arms out wide.

"Come, my boy," he cried. "Come to Uncle Haures!"

Zac kept out of sight. He ducked down low and watched as the shadows parted revealing the Angelo-demon in all his true horror.

"Oh, come on," Zac muttered as the monstrous shape stepped into view. "You have got to be kidding me."

NGELO LOOKED PREHISTORIC. Not like a dinosaur, exactly, more like the thing that had killed all the dinosaurs off. And probably without even trying.

He stood seven or eight metres tall, with his horns adding eighty or ninety more centimetres on top. The horns scraped along the ceiling as he lumbered forward, his scaly red knuckles trailing across the floor, each thunderous footstep shaking the room.

"Yes," cackled Haures. "Yes! What a specimen you are! What a specimen youa" Oof!"

The back of Angelo's hand swatted Haures across the room. The Duke of Hell was laughing with delight as he crunched into the metal barricade Zac was hiding behind. Both Haures and the barricade tumbled on for several metres, before rolling to a stop.

Suddenly exposed, Zac straightened up and locked eyes with the Angelo-demon. Bones grew like tusks from the monster's neck and jaw. The fire in his eyes burned with such ferocity it looked like the whole top half of his head was ablaze. He snorted like a racehorse after a sprint, and each time he did, rings of black smoke blew from his wide nostrils.

"What did they do to you?" said Zac softly.

"We set him free," said Haures, limping in Zac's direction. "Impressive, isn't he?" He looked the intruder up and down. "How did you get back down here, by the way?"

Zac didn't answer.

Haures shrugged. "They tried to neuter him," he continued. "Up there. They tried to smother his dark side, kill it off. But you can't kill that. How can you kill that? All they did was bottle it up. And all we had to do was take the lid off."

The Angelo-demon's fist swung down at them. Zac and Haures leaped in opposite directions and the knuckles shattered the floor where they'd stood.

"And this is what you're left with!" Zac shouted. "He's out of control. He'll tear the whole place apart."

"We'll train him," Haures smirked. "We'll break him, and we'll keep breaking him until he does exactly as we say."

"Then you're doing just what Heaven did," Zac said. He ducked as Angelo's Boa Constrictor-like tail whistled by above his head. "You're only letting him be one thing a" but now you're bottling up his angel side."

Haures snorted. "So once in a blue moon he'll lose control and do some really impressive charity work. I can live with that."

The demon duke feinted left as Angelo's tail snapped down at him. "He's already learned some basic commands," said Haures, recovering quickly. "Watch this."

Haures stabbed a clawed finger in Zac's direction. "Angelo!" he barked. The Angelo-demon's ears pricked up. It gazed down at the much smaller demon, unblinking. Haures smiled. "Kill."

Slowly, like a shadow at sunset, Angelo's gaze went to Zac.

"Don't," Zac said. "Don't do this, Angelo. You know me. Try to rememba""

A guttural howl drowned out the rest of Zac's words. The Angelo-demon charged, claws swiping, fire spewing from his cavernous throat. Zac rolled, ducked, turned, ran. All around him was the crackling of the flames and the cackling of demonic laughter and the steady boom boom boom of footsteps chasing him down.

The crumpled jail cell stood just ahead. Zac powered forward. If he could make it there, he could buy himself a few seconds. If he could buy himself a few seconds, he could come up with a plan. And if he could come up with a plan, then maybe this wouldn't have to go down as the most botched rescue attempt in the history of the human race.

The pointed tip of Angelo's tail streaked by him. There was a nerve-splitting screeching sound as the tail tore through a metal wall, and then the entire cell was jerked up into the air.

Zac saw the shadow of the metal box grow larger around him. He hurled himself out of the way just as the cell was brought smashing down against the floor.

Clambering back to his feet, Zac swung the large water gun into his hands. "I didn't want to do this," he said, taking aim. "But you're not leaving me any choice."

He squeezed the trigger. A jet of holy water hit the Angelo-demon square in the chest, but the monster didn't react.

"Immune to the effects of holy water," roared Haures. "This just gets better and better!"

Angelo brought a foot stomping down towards Zac's head. Zac avoided it, but only just, and with each miss he made, Angelo became angrier and more aggressive. If Zac was going to take the demon down, he had to do it now.

He ran from the giant demon, not trying to escape, but trying to make space. As he ran, he dug in his pocket and pulled out the little black bag Argus had given him. He heard the footsteps of the Angelo-demon thudding after him. He stopped. He emptied the bag into his hand. And then he tossed the contents towards the oncoming beast.

The eyes rattled like marbles on the hard floor. They began to roll just as one of Angelo's feet came down on them. The foot slid sharply forward and the demon became horizontal in the air. All ten circles of Hell shook when he hit the ground.

Zac and Haures exchanged a glance, then they both set off running. Zac reached the fallen Angelo first. He leaped up on to his bare chest and fired a spray of holy water towards Haures, forcing the duke to duck for cover.

"Get away from him! What are you doing?" Haures demanded, but Zac was no longer listening to him. He scrambled along Angelo's chest until he could look him in the eye.

"Angelo, it's me. It's Zac," he said. "I know you're in there. I hope you can hear me."

He paused to scoosh more holy water at Haures, keeping him at bay.

"This isn't you, Angelo," he said. "Not really. This is what they made you, up there and down here. This is what they turned you into."

A low growl rumbled from Angelo's throat, but he wasn't yet moving to attack.

"Up there they tried to make you an angel, and down here all they want you to be is a demon, but the real you is somewhere in the middle." He shot more holy water backwards over his shoulder. Haures gave a yelp of panic and leaped out of harm's way.

"Don't listen to him, boy! Listen to your Uncle Haures."

"I thought we were nothing alike, but I was wrong, Angelo," Zac said. "You're exactly like me a" not perfect, but you're not a demon, either. You're exactly like everyone." He stared deep into the fireballs that were Angelo's eyes. "The one good thing they did for you up there was give you those Hulk comics. Everyone thinks the Hulk's a monster, but he isn't. That's what you said. All he wants is for people to stop trying to hurt him. All he wants is a friend. Right? Just like you, Angelo. Just like you. That's why you love the Hulk, Angelo. You are the Hulk."

Angelo's breaths were coming more slowly now. The angry scowl on his face had relaxed just a fraction.

"Enough!" boomed Haures from down by the fallen giant's knees. The demon duke raised both hands and fire flew from his fingertips. Pain contorted Angelo's face again, and as the pain faded it was replaced by something savage. His eyes fixed on Zac. His mouth pulled into a snarl. A voice like a tropical storm roared out from within him.

"Angelo smash!"

He began to sit up, and Zac was forced to grab on to one of his tusks to stop himself tumbling to the floor.

"Yes!" bellowed Haures, dancing backwards. "Kill him. Kill the human! Kill him now!"

Zac had one chance. He gave the water gun a shake and listened to the liquid sloshing around inside it. There was a litre of the stuff left, possibly less. Even if it did work, would it be enough?

Angelo began to stand. Dangling from his tusk, Zac fired every last drop of the holy water into the demon's mouth. There was a sizzle, but a faint one. Angelo stopped rising. He looked past his nose to where Zac hung. He raised his eyebrows. And then he licked his lips.

"M-more," slurred Angelo, and the breath felt to Zac as if an oven door had been opened right in front of his face. He remembered the pistols in his waistband, thought about emptying the water into the mouth, then decided just to toss the guns in themselves. They cracked between Angelo's teeth, then he gave a low moan of satisfaction as the blessed liquid trickled down his throat.

"Y-yuummeeee..."

"That's it," Zac said. "Remember. Remember who you are, Angelo. Remember who you are."

"S-s-scrummeee..."

Zac finished the sentence for him. "In your tummy."

"What are you doing?" Haures roared. He raised his hands again and his fingers glowed white-hot. "Whatever it is, stop or I'lla""

CRUNCH!.

Angelo's tail sent him hurtling through the air again. This time Haures didn't laugh as he thudded against the far wall and slid down on to the floor.

"Z-zaaac," mumbled Angelo, his brow creasing as he struggled to form the word. Zac almost cheered.

"Yes! It's me!" he said. "Can you... can you understand me?"

Quaking with the effort, Angelo nodded his head. The jerky movement almost made Zac lose his grip, but he wrapped his other arm round the tusk and swung himself up on to Angelo's scaly shoulder.

He glanced down at what was left of the room. Over in the far corner, Haures was getting shakily back to his feet. "Want to get out of here?" Zac asked.

Angelo nodded again. He stood up, then squatted down low. "Yssss," he said, and then his legs straightened and his hands reached up and together they tore through the ceiling of the tenth circle of Hell.

AC TUCKED HIMSELF in behind the Angelo-demon's head as a chunk of the ceiling collapsed around them. The clanging of the alarm bell and the yelps of panic from the demons above rushed down to meet them, and Zac felt Angelo's muscles tense in panic.

"Ignore it," he said. "They can't hurt you. Just get us out of here."

Angelo pulled himself through the hole he had created and they emerged on to the zigzag carpet beside the fountain of blood. The nine circles of Hell stretched up above them. From down there, the first circle seemed an impossible distance away.

At least, it did to Zac. Angelo was already on the move. He crouched down low again and his legs fired like pistons, propelling them upwards. His huge hands reached out, smashed through the frosted-glass barrier, then caught hold of the edge of the seventh circle. The demons on that floor screamed and scurried for safety as Angelo reached a hand up to the sixth circle and began to climb.

"Stop them!" commanded a voice over the Tannoy system. Zac recognised the tones of the Dark Lord himself. He did not sound impressed. "The specimen must not be permitted to escape. Whoever stops them will be given the human to do with as they see fit."

Zac saw several hundred dark eyes turn to him and gleam. "Keep climbing, Angelo," he urged as the demon stretched an arm up to the next floor.

One of the larger and braver demons on the fourth circle hurled himself towards Zac, claws bared, teeth gnashing. But his leap was woefully misjudged. Zac watched the creature begin frantically flapping his arms as he fell past, then heard the distant whumpf as his face was introduced to the carpet.

The fourth circle was heaving with demons, all undeterred by the fate of their fallen colleague. They gathered near the edge, ready to hurl themselves on to Angelo's shoulders as he drew level with them.

"On three, lads!" one of them shouted. "One... two..."

Angelo opened his mouth and an inferno rolled across the corridor. The demons retreated, throwing up their arms to shield their eyes. They lowered them in time to see a foot passing by the corridor as Angelo stretched up to a higher floor.