"Get up! Get up!" Cal was shouting as he helped Will to his feet with one hand and retrieved his backpack with the other.

The boys retreated to a safe distance, then stopped, compelled to stay and watch. They were rooted to the spot, transfixed by this brute battle between cat and dog as both writhed in mortal combat, their shapes melting together until they became an indistinguishable whirlwind of gray and red, punctuated by flashing teeth and claws.

"We can't stay here!" Will yelled. He could hear the shouts of the approaching patrol, which was quickly homing in on the fight.

"Bart, leave it! C'mere, boy!"

"The Styx." Will shook his brother. "We have to go!"

Cal reluctantly moved on, peering back to see if his cat was following through the mist. But there was no sign of Bartleby, only the distant hisses and yelps and screeches.

Shouts and footfalls were now echoing all around. The boys ran blindly, Cal grunting with the effort of carrying both packs, and Will trembling with shock, his whole arm throbbing dully with pain. He could feel the blood streaming down his side and was alarmed to find that it was running over the back of his hand in small rivulets and dripping from the ends of his fingertips.

Out of breath, the boys hastily agreed on a direction, hoping against hope it would take them out of the city and not straight back into the arms of the Styx. Once on the marshy perimeter, they would make their way around the edge of the City until they found the mouth of the Labyrinth. And if worse came to worst and they missed it completely, Will knew they would eventually comet to the stone staircase again and could quickly return Topsoil.

From the sounds they were hearing, the patrol seemed to be zeroing in on them. The boys were dashing at full speed, but then they blundered into a wall. Had they inadvertently strayed down a blind alley? The terrible thought struck both of them at the same time. They frantically felt along the wall until they found an archway, its sides crumbled away and the keystone missing at its apex.

"Thank God," Will whispered, glancing at Cal with relief. "That was close."

Cal merely nodded, panting heavily. They peered briefly behind them before passing through the ruined archway.

With lightning speed, strong hands grabbed them roughly from either side of the opening, yanking them off their feet.

Using his good arm, Will lashed out with all the strength he could summon, but his knuckles just grazed ineffectually off a canvas hood. Their captor cursed sharply as Will followed with another blow, but this time his fist was caught and trapped in the iron grip of a huge hand, forcing him back effortlessly until he was pinioned against the wall.

"That's enough!" the man hissed. "Shhh!"

Cal suddenly recognized the voice and began pushing in between Will and his hooded assailant. Will was completely baffled. What was his brother doing? Feebly he tried to lash out again, but the man held him fast.

"Uncle Tam!" Cal shouted joyously.

"Keep it down," Tam rebuked.

"Tam?" Will repeated, feeling all at once very stupid and very relieved.

"But… how… how did you know we'd be…? Cal stuttered.

"We've been keeping an eye out since the escape went off the rails," their uncle cut in.

"Yes, but how did you know it was us? Cal asked again.

"We just followed the light and the noise. Who else but you two would use those bloody fool pyrotechnics? They probably heard it Topsoil, let alone in the Colony."

"It was Will's idea," Cal replied. "It sort of worked."

"Sort of," Tam said, looking with concern at Will, who was steadying himself against the wall, the rubber of his mask scored with deep gouges and one of his eyepieces shattered and useless. "You all right, Will?"

"I think so," he mumbled, holding his blood-soaked shoulder. He felt a little woozy and detached, but couldn't tell if this was because of his wounds or because of the overwhelming sense of relief that Tam had found them.

"I knew you'd not be able to rest with Chester still here."

"What's happened to him? Is he all right?" Will asked, perking up at the mention of his friend's name.

"He's alive, at least for the time being — I'll tell you all about it later, but now, Imago, we'd better make ourselves scarce."

Imago's massive form slipped into sight with unexpected fleetness, his baggy mask twisting furtively this way and that, like a partially deflated balloon caught in the wind, as he scrutinized the murky shadows. He swung Will's pack over one shoulder as if it weighed nothing, and then he was off. It was all the boys could do to keep up with him. Their flight now turned into a nerve-racking game of follow the leader, with Imago's shadow piloting them through the miasma and unseen obstacles while Tam brought up the rear. But the boys were so very grateful to be back under Tam's wing that they almost forgot their predicament. They felt safe again.

Imago cupped a light orb in his hand, allowing just enough light to spill from it so they could negotiate the difficult terrain. They jogged through a series of flooded courtyards, then left the fog behind as they entered a circular building, racing at a staggering pace along corridors lined with statues and flaking murals. They slid in the mud on the cracked marble masonry until they found themselves hurtling up stairs of black granite. Climbing higher and higher, they were suddenly out in the open again. Traversing fractured stone walkways that had long sections of their balustrades missing, Will was able to look down from giddying heights and catch views of the city below between the meshing clouds. Some of these walkways were so narrow Will feared that if he hesitated for a second he might plunge to his death in the foggy soup that masked the sheer drops on either side. He kept going, putting his trust in Imago, who didn't waver for an instant, his unwieldy form driving relentlessly ahead, leaving little eddies of fog in its wake.

Eventually, after haring down several staircases, they entered a large room echoing with the sound of gurgling water. Imago came to a halt. He appeared to be listening for something.

"Where's Bartleby?" Tam whispered to Cal as they waited.

"He saved us from a stalker," Cal said despairingly, and hung his head. "He never came after us. I think he may be dead."

Tam put his arm around Cal and hugged him. "He was a prince among animals," he said. He patted Cal on the back consolingly before moving forward to confer with Imago in hushed tones.

"Think we should lie low for a while?"

"No, better to make a break for it." Imago's voice was calm and unhurried. "The Division knows the boys are still here somewhere, and the whole place'll be riddled with patrols in no time at all."

"We keep going, then," Tam concurred.

The four of them filed out of the room and traveled along a colonnade until Imago vaulted over a low wall and slid down a slimy bank into a deep gulley. As the boys followed him, the stagnant water came up to their thighs, and thick fronds of glutinous black weed hampered their movements. They waded laboriously through, lethargic bubbles rising up and clumping together on the surface. Even though they were wearing masks, the putrid stench of long-dead vegetation caught in their throats. The gulley became an underground channel, and they were plunged into darkness, their splashes echoing around them until, after what felt like an eternity, they emerged into the open again. Imago motioned for them to stop, then scuttled up the side of the channel, squelching off into the fog.

"This is a risky stretch," Tam warned them in a whisper. "It's open ground. Keep your wits about you and stay close."

Before long, Imago returned and beckoned to them. They clambered out of the water and with sodden boots and pants crossed the boggy ground, the city finally behind them. They went up a slope and then seemed to reach a plateau of sorts. Will's spirits leaped as he spotted the openings in the cavern wall ahead. They had reached a way back into the Labyrinth. They'd made it.