"Angelo!" he shouted, although he knew it was pointless. "Angelo, where are you?"

He thrashed against the current, trying to turn and scramble for the shore, which was now just five or six metres away. That was the moment he realised the roaring sound wasn't in his head at all.

It was coming from downriver.

It was coming, he realised, from the waterfall.

Zac swore loudly. A waterfall. Argus hadn't mentioned a waterfall, and yet there a waterfall was. Zac could see the black gloop foaming and frothing as it flowed over the edge of what sounded like a very long drop.

Kicking wildly, he struck out for the shore. The sludge and the currents pulled him down like quicksand. The more he thrashed the faster he sank, and so he focused on every movement, concentrated on his technique, ignored the panic that threatened to overwhelm him.

And all the while the things that may have been necks kept coming closer.

Dark grey rocks jutted up from the water around the shore. They broke the flow, making it erratic and difficult to swim through. Still kicking, Zac grabbed for the closest rock. His fingers brushed by it as the current dragged him closer to the waterfall's edge. The sound was all he could hear now, the dark misty spray almost all he could see.

The creature in the water droned again. It was closer this time, close enough to vibrate his whole skeleton and make his teeth ache. Something brushed against his leg from below and he found the strength to grab for another jagged rock. This time he was able to hold on, and with a final, desperate kick, he dragged himself up on to the shore.

Winded and exhausted, he crawled across a ground of polished black until his arms gave way beneath him. His brain screamed at him to move further from the water. His body said it would take the suggestion on board, but warned the brain not to get its hopes up.

And Zac just lay there, breathing in the ground and listening to the fury of the falling water.

Then, despite his body's better judgement, Zac stood up. He looked back at the River Styx. Whatever had been trying to come out, had gone back in. Either that, or it had been swept over the falls. Whatever, it didn't seem to be after him any longer.

The boat bobbed on by, upside down and spinning lazily as the currents caught it and pulled it towards the edge. Zac watched it go past, heard it bump against the rocks, and then it tipped over the waterfall and was gone.

Zac kept staring at the falls, long after the boat had vanished. "Told him he shouldn't have come," he whispered, and he put the crack in his voice down to the fact that his body was still shaking with shock.

Cautiously, he approached the boulders over by the waterfall and peered down over the edge. A rainbow of blacks and greys arced out across the thundering torrent as it tumbled several hundred metres down a sheer cliff face to more rocks below.

Argus and Steropes must have known about the falls. They must have. And yet they hadn't said anything. Zac didn't think Argus had been sending them to their doom. What would have been the point? If he'd wanted to destroy them, he could've done it in person, without sacrificing his boat or the dart gun he'd handed over as they'd said goodbye.

So either they didn't know about the waterfall, which was unlikely given that Argus was apparently the all-seeing, or a" Zac turned away from the falls and gazed across the landscape beside it a" they'd travelled too far.

A path of polished onyx led from the shore towards a towering set of wooden doors. A signpost stood just off the path, its metal surface pitted with rust and stained with spots of dried blood.

Words were written on the sign in jagged black print. Zac wiped the last of the gunge from his eyes and read the text: WELCOME TO HELL.

And below that, in smaller writing: TRESPASSERS WILL BE INCINERATED.

Zac stared at the sign. He was staring so intently at it that he almost cried out in shock when something large and lumpy splattered against it at tremendous speed. Despite the force of the impact, the sign remained undamaged and intact, which was a lot more than could be said for the thing that had hit it.

The flabby body burst like a bag full of warm custard, spraying yellowish-green gunge in all directions. Attached to the body were eight or nine long appendages, which may have been tentacles and may have been necks. Whatever they were, they all stopped moving as everything that had been inside the beast exploded out through the nearest available exit.

From the shore behind him, Zac heard the hiss of rapidly evaporating water. An enormous figure with scaly red skin and lethal-looking horns and Hellfire burning where his eyes should have been, emerged from the River Styx.

Zac didn't know whether to be relieved or terrified. His mind was made up for him when the Angelo-demon began bounding in his direction, black smoke snorting from his nostrils, his face all knotted up with rage.

The demon's footsteps shook the smooth ground. Badoom. Badoom. Badoom. Zac fumbled inside his jacket and found the gun Argus had given him. He raised it smoothly and squeezed the trigger.

Nothing happened.

Zac stared into the barrel of the pistol. Scum from the Styx clogged up the hole, making firing the gun impossible.

Angelo howled and kicked out with both legs, propelling himself in Zac's direction. Leaping into a sideways roll, Zac barely avoided the demon's fists as they came smashing down, cracking the polished rock where he'd stood.

Scrambling backwards, Zac put his mouth over the end of the gun and sucked out the plug of congealed gunge. He lifted the weapon again and fired. There was a thwip as a dart cut through the air, then a faint boing as it embedded deep into the demon's neck.

Another leap. Another dodge. Another crack as Angelo missed with another punch. Two more darts buried themselves in his scaly hide and he roared with frustration more than pain.

The air around him was a ripple of heat. He lowered his horns and charged like a bull, his feet booming thunder across the obsidian ground. Zac opened fire as he retreated. A fourth dart hit the demon, then a fifth.

Before he could fire a sixth, Zac tripped on a jagged outcrop and hit the ground hard. His chin smashed against the smooth rock. A jolt of pain buzzed through his skull.

The last thing Zac saw before he passed out was the hulking shape of the Angelo-demon crashing headlong towards him.

AC WAS AWOKEN by a finger. It was poking him repeatedly in the face and was, he quickly decided, really rather annoying.

"Cut it out," he said, snapping open his eyes. Angelo was kneeling beside him, his index finger hovering just millimetres away from completing another prod.

"You're awake!"

"Well, I am now, yes," Zac said. He quickly stood up and looked around. The river was still churning over the edge of the falls, the tall wooden doors were still closed and the gun was still in his hand.

The smell, though, was different. It was the stink of fish rotting in an open sewer. It flooded his nostrils and snagged in gulps at the back of his throat. He put his arm across his mouth and nose as his eyes began to water and his saliva turned sour.

"That's disgusting," he coughed.

Angelo nodded. He was topless again, but thankfully his trousers continued to stay in one piece. "Yeah, it's that thing over there," he said, pointing at the soggy remains of the river monster, which were spread out across twenty or thirty metres. "I think it might be dead."

"You think so?"

"I'm not sure," Angelo said, missing the sarcasm. "Should we, I don't know, check for a pulse or something?"

Zac bit his tongue. "No," he said, his voice deliberate and controlled. "It's definitely dead."

"Right," Angelo nodded. "So how did that happen, then? In fact, how did I get out? The last thing I remember is sinking, and then I woke up over there." His face lit up with excitement. "You saved me! Didn't you? See, I told you we make a great team!"

"How would me saving you make us a great team?" asked Zac. "Anyway, you got yourself out."

Angelo frowned. "Oh. Did I? I don't remember that. Are you sure?"

Zac took off the backpack and slipped the gun inside. "Pretty sure."

"Well... OK," said Angelo, shrugging his bare shoulders. He stepped past Zac and studied the signpost. Some of the letters were hidden beneath monster remains, so the sign now read: COME TO HE.

"It says Welcome to Hell," Zac explained. "You know, under the gunge and monster bits."

He stared hard at the wooden doors, as if trying to see through them to whatever lay beyond. "You sure you want to do this?"

Angelo still didn't hesitate. Despite everything that had happened to him, he still didn't hesitate. Even Zac had to admire that. "Yep."

"It'll be safer out here."

The angel-demon glanced back at the Styx and shivered. "I'm not sure it would be."

"Well, clearly it would," Zac insisted. "Being outside Hell would be safer than being inside Hell."

"Yes, but would it?"

"Yes."

"Ah," said Angelo. "But would it?"

"Yes, it would! Obviously. I mean, think about it."

"That's as may be," Angelo said, nodding sagely, "but would it really bea"?"

"Forget it," Zac snapped. He adjusted the rucksack on his shoulders as he stomped off towards the door. "You coming then, or what?"

"Yippee!" said Angelo, skipping on bare feet across the polished floor. He caught up with Zac just as he arrived at the doors. They both leaned back and craned their necks and looked up.

The doorway was fifteen, maybe twenty metres high, and wide enough to drive two tanks through side by side. The wood of the door was dark and smooth, with two handles made of grey crystal mounted at about Zac's head height.

Angelo whistled quietly. "That's a big door."

"It is."

"I wonder why they need such a big door."

"I'm trying not to wonder that same thing," Zac said. He reached for the handles, but neither one turned. He tried pushing the doors, then pulling them. Neither one budged.

"What now?" asked Angelo.

"Not sure," Zac admitted. He gave the door a final dunt, then turned his attention to the walls on either side. "Wait, look at this."

Angelo was at his back in a heartbeat, leaning over him, trying to see. "What? What is it?"

Zac studied the metal and plastic box attached to the wall. It had a button marked CALL, and what looked like a small speaker directly above it. "I think... I think it's an intercom."

"Oh," Angelo said. He nodded slowly. "What's an intercom?"

"It's like a telephone thing. Press the button and you can speak to whoever is on the other side."

Realisation spread across Angelo's face. "Right, one of those. Oh, wait! I just thought of something!"

"What?"

"Star Wars! There's this bit in Star Wars, right? When Luke and Han Solo are trying to rescue Princess Leia from the Death Star, but she's, like, being guarded and everything." Angelo bounced up and down with excitement. "So to get in, they dress up as Stormtroopers and put Chewbacca in handcuffs and pretend to have captured him!"

"Right," Zac said. "And what then?"

"They rescue Princess Leia."

Zac hesitated. "OK. And how does that help us?"

Angelo smiled uncertainly. "What?"

"Han Solo and Luke Skywalker. They dress as Stormtroopers and put Chewbacca in handcuffs. How does that apply here?"

Angelo shrugged. "Well... it doesn't."

"What? Why the Hell did you tell me, then?"

"Just that it's one of my favourite bits," Angelo explained. "Han Solo uses an intercom. That's what reminded me."

Zac slapped himself on the forehead. "Oh, for fa"" he began, before a crackle from the wall-mounted speaker stopped him. A not-unpleasant female voice addressed them.

"Welcome to Hell, dominion of the Dark Prince Satan and all his underlings. Your misery is our satisfaction. How may I be of assistance today?"

Zac's mind raced. They'd lost the element of surprise, so there was nothing to gain from keeping quiet. But what could he say? How could he explain who they were and why they were there?

"Hello?" said the voice on the intercom. Zac was about to reply when Angelo stepped past him and approached the speaker. He gave Zac an exaggerated wink, then began to talk.

"Bg," he said. "Pk. Sshk."

There was a pause from the other side. "Sorry? I didn't catch that."

"Brrrk. Tsst. Jb?" Angelo said, then he bit his lip to stop himself laughing.

"Sorry, we seem to be having technical difficulties," the woman said. There was a note of irritation in her voice. "One moment and I'll come on out."

Angelo stepped back, put his hand over his mouth, and mimed laughing. There was a clunk and a creak and the doors began to swing slowly outwards.

A moment later, a woman in a grey business suit came through the widening gap. Two stubby horns poked up through her greying hair, and as she stepped on to the onyx ground her hooves clipped and clopped.

"Sorry about all that," the woman said. She smiled, but it wasn't a real smile. It looked as if she'd learned it from a book, and not a very good book at that. "Now, how may I help you, gentlemen?"

A dart from Zac's gun lodged in her cheek, just below a pointed ear. Her eyes glazed over at once. "Well, isn't that just marvellous?" she slurred. A second later, she was asleep on the floor.

The smile fell from Angelo's face and he pointed down at the slumbering demon woman. "You shot her!" he gasped. "You shot her in the face. I can't believe you shot her in the face!"

"I thought that was the point," Zac replied. "I thought that was why you lured her out?"

"I wasn't luring anyone out, I was just having a laugh!" Angelo yelped. "I didn't know you were planning to shoot her in the face the minute she stepped outside!"

"It's just a tranquilliser. She'll be fine."

"You hear that, missus?" asked Angelo, leaning over the woman and raising his voice. "It's just a tranquilliser. You'll be fine." He watched her motionless body for a few more seconds. "Oh, look, that's perked her right up, that has."