I looked back. Klicks had managed to push the main hatchway almost shut, but a troodon arm still stuck around the edge. I heard the crack of breaking bone as Klicks threw his massive shoulder against the door, but the beast held on, its opposable claws snapping open and closed.

I ran for the equipment lockers next to the dead troodon and found the metal box containing my secondary dissection kit. I hurried down the ramp to join Klicks in the cramped access-way. While he continued to fracture the invader’s arm with brutal body slams to the door, I used my bone saw to hack through the limb. Blood spurted everywhere. At last, the arm fell to the floor, twitching, and Klicks and I forced the main door shut. I then dashed up the ramp into the habitat proper and relayed boxes and pieces of equipment down to him. He rammed them up against the door as a barricade. It wouldn’t hold for long.

The main doorway had been our one aperture for firing at the troodons. No — wait! I could shoot through the instrumentation dome. I scrabbled up the ladder into the cramped space. The vertical slit was still open. I rotated the whole thing to bring the opening around to face west, stuck the barrel of my elephant gun through the slit, and squeezed off eight rounds as fast as I could reload. The gunshots echoed deafeningly inside the glassteel hemisphere. Three of my shots missed completely. Three more found solid targets, killing the closest of the troodons. The last two injured a pair of the dancing beasts, hitting one in the right leg, the other in its left shoulder. Both collapsed to the ground.

The parasaurolophus was bellowing commands at the top of its lungs, the two separate nasal chambers that ran through its trombone-like crest each producing separate notes, harmonizing with itself. Apparently responding to the order, one of the triceratopses charged the Sternberger, its haunches pumping up and down as it ran. The ship rocked under its impact, and I was almost knocked off my feet. I tried to kill the horned-face, but my bullets just nicked tiny shards off its bony neck frill. Still, it was something of an impasse: no troodon could approach the ship without me picking it off.

The parasaurolophus barked again. Moments later the sky went dark. A great shadow passed over me. A huge turquoise pterosaur, its vast furry wings spanning a dozen meters, was flapping its way toward the instrumentation dome. Judging by the curving snake-like neck and the incredible size, this was either Quetzalcoatlus or a close relative, a genus known to range from Alberta to Texas at this time. I scrambled to reload, but in my panic sent the box of shells spilling across the floor, half of them rolling out the opening for the access ladder. By the time I was ready to fire, the dragon filled my field of view. My shots tore holes in its turquoise wings, but the pterosaur continued to swoop in, its claws sounding like chalk on a blackboard as they scrabbled for footing on the smooth metal hull of the Sternberger.

The head with its long narrow beak slipped through the observation slit, poking at me from the end of a serpentine three-meter neck. I scrunched myself back against the far wall of the dome. Holding the rifle in both hands, one on the painfully hot end of the twin barrels, the other on the wooden butt, I tried to ward off the creature. Fat chance. Moving with eye-blurring speed, it seized my gun in its jaws and twisted the weapon free with a sharp jerk of its neck. Before I realized what had happened, the beast had taken to the air again, the rifle clamped in its beak. My hair whipped in the breeze caused by the downward thrust of the immense blue-green wings.

There was no point in staying in the dome. I closed the slit, then backed down the ladder. Klicks was pushing the food refrigerator down the ramp that led to the exterior door. I guess he intended to use it to strengthen the barricade.

My heart jumped. "Oh God—"

"What is it?" Klicks said, looking up.

"Your leg."

A grapefruit-sized mound of phosphorescent blue jelly was throbbing on the shin of Klicks’s khaki pants. It must have come from the troodon I’d killed earlier, the one slumped by the equipment lockers next to where the fridge had been. Klicks frantically undid his belt and pulled the trousers off, flinging them across the accessway. They hit the wall with a wet splat and stuck. But the Het had been having no trouble percolating through the cotton weave and some of it was still on his skin. Klicks was near panic. I grabbed a scalpel from my dissection kit and scraped the dull edge of its blade across his shank, gathering up pieces of Martian. After each stroke, I flicked the knife, sending dabs of blue jelly flying into the dissection-kit box. A minute later I looked up. "I think I got it," I said.

"All of it?" Klicks sounded desperate.

"Well … most of it, anyway. Let’s hope there’s enough Deliverance left in your system to prevent what did get in from interacting with your cells."

"What about that?" he said, pointing at his pants.

I got a pickax and used it to knock the trousers off the wall into a stasis box, then tossed in the dissection kit as well and slammed the silver lid shut. We went up the ramp and back into the main habitat.

Suddenly the ship rocked again as a pair of white triceratops horns burst through the side of the hull. The Hets must have learned from their brief mind-melds with us that the Sternberger was like a yo-yo, attached by a mathematical string to the Huang Effect generator 65 million years in the future. Even partially smashed, the timeship would still dutifully return to its launch point in midair between the Sikorsky Sky Crane and the ground. It didn’t have to be intact, but they did have to be inside its walls.

The ship buffeted once more, its hull deforming where a second triceratops rammed against it. Moments later there was another impact, and another pair of horns pierced the wall, this time less than a half-meter from my head.

The parasaurolophus’s call split the air again. Outside the window, the giant tyrannosaurs, looking like blood clots the size of boxcars, growled in response.

"We’ve got to do something," I said.

"Good thinking, genius," said Klicks. "What should we do?"

"I don’t know. But we can’t let them have access to the future. Christ, they’d take over the whole planet." The ship rocked again, another triceratops smashing into it. "Dammit!" I slammed my fist against the wall. "If only we had some weapon, or … or, hell, I don’t know, maybe some way to turn off the gravity-suppressor satellites."

"A coded signal in binary," said Klicks at once. "1010011010, repeated three times."

"Christ, man, are you sure?"

Klicks tapped the side of his head. "The Martian may be dead, but his memory lingers on."

I was over to our Ward-Beck radio unit in two bounds and flipped the master switch on the black and silver console. "Do you think we can get a signal to the gravity satellites?" I asked.

Klicks squinted at the controls. "The satellites are obviously still in good working order," he said. "And the Hets do use radio in very much the same way we do."

"What about the satellites below the horizon?"

"The off signal will be relayed by those satellites that do receive it," said Klicks. "We only have to connect with one. That makes sense, of course; otherwise, there’d be no way to operate them all from a single ground station."

"Won’t we need a password to access the satellite computers?" I asked, peering at the console, trying to remind myself of what all the buttons did.

"You said it yourself, Brandy. The Hets are a hive mind. The concept of ‘passwords’ is meaningless to them."

I reached for a large calibrated dial. "What frequency should the signal go out at?"