As the hissing sound grew louder and clearer, it became a surging ocean, but it also gained definition.

“It’s screaming,” Gina shouted.

“It’s all of them, all the hybrids. It’s their rage, shared like they share everything.”

“Then we’re winning. We’re making progress.”

“That’s what they want us to think.”

Then the sound seemed to focus in front of them, and it began to rise. Soon it was so loud that Mark saw blood coming from Gina’s ears and knew that his were bleeding, too, and still it rose, until something that does not happen in the human world did happen: the sound became a gleaming thickness of motion … and then swirling, twisting in on itself, thickening, more it became a screaming shadow, and then it became a creature.

At first, he did not understand what he was seeing—a huge snake or a great, gnashing crocodile—but as it rose to its full height of at least eight feet, he found himself facing a reptile with a long lizard’s face and silver, shining eyes that communicated nothing remotely close to a reptile’s dead stare. Beneath their sleek, angry ridges, the eyes were those of an evil masterpiece.

“You cannot win,” it said, its voice caressing the air with graceful authority, in a tone infinitely more subtle than the finest, richest voice that either of them had ever before heard.

He did not think that they could beat this thing, though, and he decided that they had better not try.

“Run,” he said. “Follow the rats.”

But she remained as if glued in place, her lips slack, her eyes riveted to its eyes. A shadow reached out from the darkness of its body, its movement easy, but careful. It focused into long fingers with wine red nails, which delicately brushed her cheek. Steam rose from her skin, and she grabbed the spot with a cry. The shimmering darkness of the thing was not a color at all. It was the darkness of great heat.

Mark grabbed her, pulling her away.

“It’s created a demon,” he said.

“Or conjured one.”

“They don’t exist.”

“Unless they do.”

But then, moving more quickly than even he could move, this new kind of creature, its body hyperphysical, and its mind unimaginable, reached out, slapping its palm against her temple. Screaming, she began to fight Mark, clawing at him, but then he broke her contact with the creature, and the scream stopped, and she clutched him.

“It had me,” she cried, “oh, God, Mark, it had me in my mind.”

“This really is the fourth generation. We need to proceed.”

She sucked breath. “Will it let us?”

The creature crouched, now appearing much more solid. “This is its real form,” Mark said.

It extended powerful arms. But where were its weapons? Where were its helpers? Then he realized, this newest design was like them, itself a weapon.