Leo opened the door to the cargo bay once more, but this time it was Mikey on his left, Donnie behind him.

"Do you think it will attack?" said Mikey. Even with his voice lowered, the noise echoed in the large space.

"It might," said Donnie, quieter. "It knows we're enemies now."

That thought hovered over them as they slipped through the door, huddled together so they could watch all directions. An ache gripped Leo; memory and nostalgia for the times on Earth when they had gone hunting like this, creeping along darkened alleyways, stealthy, aware, watching each other's backs. It was so familiar and comforting that Leo wanted to stop and savour it for a moment, pretend that they were as they had been, pretend that all the bitterness and conflict was yet to come.

But instead of a sword, Leo carried a laser saw; Mikey had the graphene extinguisher, and Donnie held the canister for the neutrinos. There was no going back. If they were going to survive, they had to get through this.

On the other side, there would be time for more. Leo made a silent promise to himself. To his brothers.

They came out from between the stacked cargo and paused. Donnie stepped into engine room, then backed out hastily. "Okay, we have a problem. It's on the reactor."

"What's going on?" said Raph over comms.

Leo didn't waste breath replying. He slipped up beside him and peered through the hatch. The space worm was a black, pulsing mass on the reactor. "Is it feeding?" He couldn't imagine what would happen if it got bigger, stronger.

"No. The reactor has shielding. I guess it knows that's where the food is, but can't get to it."

Well that was a small relief. "How do we get it off there?"

"Extinguisher," said Donnie.

Leo nodded and motioned Mikey forward. Don pressed against the wall near the hatch, ready to leap through. Mikey crouched on the other side. Leo stood in the opening and turned on his saw. A big, shiny target.

"Now," he said to Mikey.

The extinguisher went off with a roar, shooting a cloud of graphene at the space worm. It flashed away from the reactor and rushed toward the hatch. Leo ran, dodging to the side, remembering how fast it was. He bolted between the stacks, waiting for the chill grip, shoulders hunched in anticipation of a cold grip. But nothing came at him. He glanced behind him, but couldn't see a shadow. He slowed, swung around, saw up. Nothing.

"Where is it?" said Raph's voice through the speakers, at the same time as Mikey yelled "Where did it go?", his voice bouncing off the metal walls. He was somewhere to the left of Leo, in another alleyway between the stacks, he guessed. "Raph, can you see it on any of the cameras?"

"No." The cameras were trained on the cargo bay doors, there to track coming and going. Not to record inert cargo. Leo jerked the saw up at a sound above him, only to see Mikey's face appear over the edge of the stacked cargo.

"Mikey." He couldn't keep the relief out of his voice. "Where's Donnie?"

"In the engine room."

"We'd better circle back in case it traps him in there. Stay close to me." Leo hurried down the corridor, sweeping the walls, the shadows, looking for darkness that moved. They positioned themselves in the doorway to the engine room. Leo glanced behind him. Donnie was bent over the reactor connection to the engine, working at the valve. The radiation alarm went off.

"Donnie—"

"Ignore it," he snapped.

Leo grimaced. The alarms weren't meant to be ignored. They screamed at him something is wrong and he silently agreed with them.

"Radiation warning," said Raph over comms, as if they couldn't hear it. "What's happening?"

Leo bit back his desire to silence Raph. It wasn't his fault. He never did handle incapacity well. "Donnie's filling the canister. Nearly there. How are the Kraang?"

"Closing in."

Now he wished he hadn't asked. He tried to put the Kraang out of his mind. Nothing he could do about them.

"Here it comes!" yelled Mikey.

A shadow swept across the ceiling, lightning fast. He and Mikey locked shoulders, standing between the worm and Donnie, working frantically in the engine room. It flowed across the ceiling above them. Mikey gave it a blast of powder. It jerked back, but didn't retreat.

"How much brain do you think it has?" said Mikey.

"Not much, I hope," he said, as the shadow slid from one side to the other, clearly indecisive. Yes, look, we're scary, you don't want to take us on.

"Got it!" shouted Donnie from behind them. Leo heard the clang as Mikey dropped the extinguisher, the slap of the canister on Mikey's hands, and then Mikey was off across the cargo bay, waving the canister above his head. "Come on, wormy! Din-dins!"

The space worm surged across the ceiling and dropped down in front of Mikey, who yelped and changed direction.

He's not fast enough, thought Leo, dashing across the bay. "Mikey! To me!"

"What's happening?" said Raph.

Mikey tossed the canister and Leo caught it. He turned and ran down the long corridor between the stacks, feet ringing on the metal floor. There was the door, getting closer, but there was the shadow above him.

"Up and over, Dude! Go long!"

"What's happening?" Raph shouted.

Leo sent the cannister up in an arc over the cargo. The worm raced after it. Leo climbed the cargo stacks and ran along the top. The worm out of sight. Leo leaped the gap and looked down.

Mikey was cornered. Leo was closest to the hatch. Time for a change of plans. "Mikey! Here!"

Mikey tossed him the canister. He bolted for the end of the stack and jumped. The impact shot up through his knees. He staggered and dived through the hatch. Adrenaline sluiced through his system. How close was it? Could he make it? His feet pounded on the decking plates. Keep moving. Keep moving. The narrow corridor closed in around him. He couldn't stop to look behind him. Every moment he anticipated the cold touch. Through another hatch, and then he was in their tiny armament bay. The torpedo tube was open and waiting. He turned.

The space worm was right behind him. He froze in terror as the blackness spread over him. He shoved the canister in the tube. Go after it, go after it!

The worm flowed off him and he fell, but it wasn't crawling into the tube. It had extruded part of itself into the narrow space after the canister. Leo kicked it, but it was like kicking rubber, and had as much effect. His mouth was dry, and his stomach roiled. Too much radiation, he thought distantly.

"Duck, bro!"

Leo rolled away. Mikey sprayed the worm with the extinguisher. It flowed into the tube and Mikey slammed the door.

Leo hit the button which would pressurise the tube and send the contents shooting out into space. "Go, Raph! Jump!"

"I can't! Engine's still offline!"

The ship rocked, throwing them against the wall.

"And the Kraang are pissed!" he said.

It was over. Leo met Mikey's gaze, blue and solemn. "Fire all torpedoes," he said, his voice gravel and glass. Might as well go out in a blaze of glory.

The ship rocked again. The lights went off, then flickered on again. A long low siren wailed, drowning out anything they might want to say. Hull breach. The shields must be down. Not long now. Mikey's hand fumbled for his. He gripped it.

A cool detachment washed over him. This was the end. In the fog of acceptance, a sting of regret. There was still something he needed to say, to Donnie, before he died. He opened his mouth. "Donatello, I-" It was no good. There was too much noise. He swallowed bitter regret. He didn't want to die with this thing unsaid between them.

The deck vibrated beneath his feet as the engine rumbled to life. Too late, he thought, as the world dissolved around them.

He came back to himself, lying on the floor with Mikey draped over him, the taste of ash in his mouth, deafened by the warning klaxons.

"Holy shit," said Mikey, raising his head. "Did we make it?"

Raph's voice came over comms. "We're down to 2% oxygen."

Leo stared at Mikey, his brain not ready to accept that they had made it. Mikey, always the first to bounce back from a crisis, yelled and thumped him on the shoulder. "We made it! Woohoo! We rock!"

Leo grinned at him, though he hoped it didn't look as sick as he felt. "Suit up and head for the cockpit, guys. Raph, I'll bring your suit up. And save me some iodine."

"Oh, no problem. I've got plenty. You'll love it."

In the hanger, he was halfway into his suit when Donnie limped in. Mikey slipped away discreetly with Raph's suit. Donnie hesitated near the suit cupboard.

Leo stepped aside so he could get to his suit. He thought of all the things he'd wanted to say when the Kraang torpedoes had been pounding them. The words seemed harder to say now. He opened his mouth, closed it again. "Great timing," he said finally.

Donnie's mouth twisted in a wry smile. "Thanks." He paused, his eyes shifting away from Leo's face, then back. "Good plan."

Leo heard the unsaid this time. "Thank you." There was fluid oozing through the gauze on Donnie's arm. That was going to be murder in a suit. "Let me give you a hand." He stepped forward.

Donnie's face closed over. "I'm good, thanks." He turned his back on Leo.

Leo stood frozen for a long moment as Donnie pulled out his suit. I should help him anyway. That's what he wants. But his judgment on what Donnie wanted was no longer reliable. Would it fix things, if he just helped anyway, or would it make things worse? Would it open up the festering wound between them and break them apart once and for all?

He didn't have the courage to find out. He zipped up his suit and headed for the cockpit.