"Which one?"

"What do you mean?"

"Fur, or leaves. Which one?"

"Well, both. They looked like they were growing out of each other, all over its body."

McShay searched Pruett's face, feeling uncomfortable when he saw no sign of contrition; in fact, there was shock and disbelief there, and that made him feel worse. Moulding suddenly grew tense, his gaze fixed on the monitors. "It's coming this way," he said quietly.

Unconsciously, McShay turned towards the security door. Through it he could hear a distant sound, growing louder, like the roaring of a beast, like a wind in the high trees.

"The temperature's rising in the reactor core," Nelson called out from the other side of the room. The second tonal emergency warning began, intermingling discordantly with the intruder alarm; McShay's head began to hurt. "The fail-safes haven't kicked in," Nelson continued. He pulled out his mobile phone and punched in a number; McShay wondered obliquely who he could be calling.

"It's nearly here," Moulding said. McShay couldn't take his eyes off the security door; he was paralysed by incomprehension. That horrible noise was louder now, reverberating even through the shielding. He couldn't understand how the troops could remain immobile with all the confusion raging around them; their guns were still raised to the door, barrels unwavering.

The one in charge glanced briefly at McShay, then said, "If it comes through, fire the moment you see it."

What's the point? McShay thought. It's been in the reactor core and its still alive! He was overcome with a terrible feeling of foreboding.

There was a sudden thundering at the door and it began to buckle like tinfoil; McShay thought he could see the imprints of hands in it. Despite their training, some of the troops took a step back. The roaring which sounded like nothing he had ever heard before was now drowning out the alarms.