Chekhov and Sulu lurched as the ship was rocked by another explosion. Sulu braced his hand on the nearest shelf and Chekhov held onto the table as the aftershocks reverberated through the Enterprise. He gave Sulu a look full of intensity.

"Remind me not to make our Science Department angry," he muttered, "They seem to be quite good at quickly making deadly weapons."

"It's not the weapons that scare me," Sulu said, "It's all those viruses they've got stored."

Sulu hadn't looked up from the photon grenade in his hand but Chekhov understood. Perhaps this was better - meeting the enemy head on and armed, instead of lying in a biobed waiting for death to come.

The next explosion was closer. The sound was not as muffled. Gunfire erupted like multiple cracks of distant thunder.

"They're moving," Sulu said, grimly, "Getting closer to the Bridge. We have to go."

"I have seventeen done," Chekhov said, adding the last one to the bag at his feet.

Sulu grinned like a hungry wolf, "Nineteen," he said, "I beat you by two."

"I was trying for accuracy," Chekhov said, rising and slinging the strap on the bag over his shoulder, "I didn't want to blow us up on the way to getting us blown up." The Russian had kept his tone light and he tried to smile bravely but his eyes were haunted and restless. "Besides, I took time to recalibrate this to track these Cossacks."

He held up a tricorder before putting it over the other shoulder.

"Good," Sulu, then added, "Spock would be proud of you."

Pain flashed quickly across Chekhov's face. "Mr. Spock would tell you that pride is a human emotion and it's my duty to learn as much as he can teach me."

"Yeah," Sulu agreed, but something in his eyes said he wasn't convinced, "That's what he would say."

Using the table they hoisted themselves up into the ceiling once again. They crawled carefully through the white metal tunnels, heading in the direction of sounds they should have been fleeing from. As if in a nightmare, where time slowed down and everything seemed magnified, they tracked down pockets of invaders, dropped grenades on them and scrambled away as quickly as possible. Sulu had ordered a 20 second delay on the detonation. It wasn't a lot of time to get away in the tight confines of the ducts. Many times they made it to safety just as the ceiling behind them collapsed in slow motion smoke and flame. But there wasn't time to be terrified either, as much as they wanted to be. There wasn't time to be sick though their stomachs churned at the carnage, the smell of blood and death and burning ozone. There wasn't time to cry or mourn when they crawled over grillwork that revealed fallen shipmates mutilated, some beyond recognition, some too horribly recognizable.

They had arrived at one vent milliseconds too late to stop the instant deaths of Martha Landon and Kyomoto, a botanist who had been pestering Sulu for weeks about his collection of plants. Martha had uselessly fired a phaser at the invaders, facing them with defiance and too much bravery. An alien had put a bullet in her forehead with pinpoint accuracy and no mercy. It had taken three bullets to stop Kyomoto as she had ducked for cover. Wretched with regret at the further mutilation of their comrades, Chekhov had tossed a grenade out the grill to the floor.

He had wanted to watch, to see Martha's killers blown into nothing. Only Sulu's urgent order put him in motion. A spray of gunfire ripped the ceiling behind him just before it blew up.

They fled around a bend, followed a descending shaft for a short time and stopped for breath when they came to a corner. For a moment Chekhov collapsed onto his side, his head pillowed on his forearm, his eyes closed. Sulu waited, watching. Chekhov was his best friend, his cohort in mischief and mayhem. He knew that Chekhov had broken it off with Martha at least a year ago, but they had remained friends. Her death was like a hammer stroke to Chekhov. The vicious and unprovoked attack had taken the bright, vivacious spirit that was Chekhov and dragged him, down, down, into unyielding dark.

"Pav," Sulu said, softly. His own soul was in agony, but there was an ancient samurai screaming inside it to keep going.

Chekhov opened his eyes and Sulu saw a flame of sorrow and hate burning there. The Enterprise shuddered again beneath them.

"Deck Nine," Sulu guessed.

"The Science Labs," Chekhov exhaled. His muscles screamed in protest but he rolled to his knees and settled the bag of remaining grenades on his back. "Let's go."

They made their way downward, blocking the sounds of a world gone mad as those same sounds grew louder and louder. When they could hear heavy booted feet marching towards them, Sulu stopped over a grate and sent Chekhov ahead to the next one down the tunnel. The order was wordless after that. They unscrewed the grillwork and waited to flank the oncoming platoon.

"Sulu," Chekhov hissed.

"What?" Sulu whispered back, annoyed.

"It's been good to serve with you," Chekhov replied.

Sulu's throat constricted with hard emotion but there was no time to reply. The platoon of marauders rounded a corner and was there beneath them. The grenades dropped but this time - perhaps warned now by the other roving bands of aliens - their enemy reacted, firing deadly weapons into the ceiling.

Their world erupted into shards of pain and blinding light. Sulu was vaguely aware of Chekhov screaming in mortal agony just before the explosion shattered the ceiling and the conduit. He was falling, his body flaming with pain.

And then only silence and darkness reigned.