"What's he doing?" Marquis asked. One of the console panes showed him Watson and several others clustered around the axial corridor's pressure door.

"Sir, he's killing people, shooting them!" Watson's voice had risen to near hysteria.

"What sort of weapon is he using?"

"I don't know. He's got some kind of pistol, but I didn't see it fire. Hey, there's another person through there with him. They're wearing some kind of spacesuit, I think. He's putting something on the door."

"Get back, now," Marquis ordered.

"I can't see what it is."

The camera showed Watson pressing his face against the pressure door viewport.

"Get away from the door. That is an order."

Watson moved back reluctantly, gripping the rungs along the axial corridor. A brilliant white light stabbed out from the pressure door. It vanished as dirty black smoke poured out; streamers churned along the corridor walls like a fast-moving oil slick. A disk of flaming composite suddenly tumbled out of the smoke, narrowly missing Watson.

"Secure that section," Marquis Krojen ordered the AS. "I want physical isolation."

"Affirmative," the AS replied. "Closing emergency pressure doors along the axial corridor."

"Captain." Simon Roderick's face had appeared on one of the console panes. Just his face, against a neutral gray background.

"What have you let up here?" Marquis demanded. He didn't care about etiquette now. His ship was suffering.

"We believe there is an alien on board the spaceplane," Simon Roderick said.

"What?"

"An alien," Roderick said imperturbably. "It has human allies who will probably try to hijack the Koribu."

"Over my dead body." Marquis watched a camera image of the axial corridor. The Skin and his spacesuited companion were through the emergency pressure door. They stopped where there was some kind of access panel on the corridor wall, and the spacesuited figure took out a power blade.

"Let's hope it doesn't come to that," Roderick said.

"The intruders have exposed a network node," the AS said. "Subversion software is loading directly into the local neurotonic pearls. It is reconfiguring their processing patterns."

"Stop it," Marquis said.

"I am unable to comply. Network data management routines have been corrupted. Firewalls established. Power and environmental support withdrawn."

"Holy Jesus." Marquis studied the starship's primary schematic. They'd lost all contact with the rear third of the Koribu, which now lay beyond the firewalls and closed emergency pressure doors. "What can this alien do?"

"I'm not sure," Roderick replied. "But it has technology well in advance of ours. You might not be able to stop them."

"Break out the weapons," Marquis ordered. "I want our crewmen armed and authorized to shoot."

"We've got ten carbines and some dart pistols," Colin Jeffries said. "They'll just bounce off Skin."

"But maybe not the other one."

"I am detecting venting from the isolated cargo sections," the AS reported.

"Venting what?" an aghast Marquis asked. The panes shifted to views from external cameras. Huge plumes of glittering silver vapor were fountaining out of the starship's rear sections.

"Spectrographic analysis indicates it is our atmosphere," the AS said.

The doctor refused to cooperate at first. Simon didn't actually threaten him, but he came close before the man's more basic survival instinct cut in.

"I really don't recommend this," the doctor said. He was helping two orderlies push Simon's trolley and three cabinets of intensive-care support equipment through the spaceport terminal building. "You're not stable enough for something as traumatic as a spaceplane flight yet. Please reconsider."

"No," Simon grunted. He could hear his Skin escort shouting at people to get out of the way. Protests and hurried scraping sounds. Trivial background details he ignored.

An optronic membrane was covering his remaining eye, showing him camera images from the Koribu and the space-planes around it. Gas was still venting from the fat barrel of its cargo section. There must have been twenty of the plumes, emerging from hatches and valves distributed among the silos. His communication link to the starship buzzed with confused, shouted orders and queries. Crewmen were struggling into spacesuits, collecting weapons from the executive officer. As countermeasures went, it was truly pitiful.

The starship's AS was completely ineffectual against the alien's Prime program. If Newton and the other (presumably an enhanced villager) kept going along the axial corridor and physically loaded it into every section, they would soon have complete control. His personal AS now considered this was their most likely strategy. The most uncomplicated and efficient way of hijacking a starship, with a frighteningly high projected success level.

Simon saw a small silver sphere fly out from the cargo section.

"What was that?" he asked.

"Lifeboat," Marquis Krojen said. "There's very little air left back there. My crew is having to abandon the contaminated area."

Simon's trolley wheels bumped over a small ridge on the floor. He moaned at the sharp flare of pain that the jolt inflicted.

"Sorry," the doctor said. He didn't sound it "Can the engineering shuttles close down the venting?" Simon asked.

"Some of them, possibly. But there's not enough time."

Several of the plumes were shrinking, becoming less energetic.

The trolley was pushed into an elevator. Simon's magnetic sense showed him almost a dozen people clustered around him as the doors slid shut.

"Damn," Marquis Krojen exclaimed. "They just blew another pressure door. That puts them above the first life support wheel."

"Where are your people?" Simon demanded.

"I'm putting a squad together. We're not trained for this, not fighting a Skin."

"Learn fast." Simon saw another two lifeboats shoot away from the Koribu's cargo section.

"The subversion software's loading," Marquis Krojen said. "We're losing another section."

"Can they take over the life support wheel?"

"Not directly. The AS inside will firewall the wheel. But controlling the axial corridor gives them the power and environment feeds to the wheel."