Mark's grip tightened convulsively. Miles checked once more for unwanted company—the tube was still empty—and thrust over the side.

Their doubled weight gathered momentum terrifyingly. They fell unimpeded in near-silence for four stories—Miles's stomach was floating near his back teeth, and the sides of the lift tube were a smear of color—then the rappelling spool began to whine, resisting its blurring spin. The straps bit, and Mark's grip hand-to-hand across Miles's collarbone began to pull apart. Miles's right hand flashed up to clamp around Mark's wrist. They braked to a demure stop a centimeter or two above the lift tube's bottom floor, back in the belly of the synthacrete mountain. Miles's ears popped.

The noise of their descent had seemed thunderous to Miles's exacerbated senses, but no startled heads appeared in the openings above, no weapons crackled. Miles and Mark both nipped back out of the line of sight of the tube, into the little foyer off the tidal barrier's internal access corridor. Miles pressed the control to release his grappler and let the spool rewind; the falling thread made no noise, but the grappler unit clinked hitting bottom, and Miles flinched.

"Back that way," said Mark, pointing right. They jogged down the corridor side by side. A deep, growling vibration began to drown lighter sounds. The pumping station that had been blinking and humming when Miles had first passed that way was now at work, lifting Thames water to high-tide sea level through hidden pipes. The next station down, previously dark and silent, was now lit, preparing to go into action.

Mark stopped. "Here."

"Where?"

Mark pointed, "Each pumping chamber has an access hatch, for cleaning and repairs. We put him in there."

Miles swore.

The pumping chamber was about the size of a large closet. Sealed, it would be dark, cold, slimy, stinking, and utterly silent. Until the rush of rising water, thrumming with immense force, gushed in to turn it into a death chamber. Rushed in to fill the ears, the nose, the dark-staring eyes; rushed in to fill the chamber up, up, not even one little pocket of air for a frantic mouth; rushed through to batter and twist the body ceaselessly, roiling against the thick unyielding walls until the face was pulped beyond recognition, until, with the tide, the dank waters at last receded, leaving—nothing of value. A clog in the line.

"You . . ." breathed Miles, glaring at Mark, "lent yourself to this . . . ?"

Mark wiped his palms together nervously, stepping back. "You're here—I brought you here," he began plaintively. "I said I would. . . ."

"Isn't this a rather severe punishment for a man who never did you more harm than to snore and keep you awake? Agh!" Miles turned, his back rigid with disgust, and began punching at the hatch lock controls. The last step was manual, turning the bar that undogged the hatch. As Miles pushed the heavy beveled door inward, an alarm began to beep.

"Ivan?"