Without even having met her, he had thrown away everything to come to her aid. When he'd finally met her face-to-face, she'd scared him more than Lubin had. But something had happened to Clarke since then. The ice-queen affect hadn't changed at all, but something behind it seemed—smaller, somehow. Almost fragile.

Alice didn't seem to notice, though. She'd been been the rifters's self-appointed mascot from the moment she'd seen a chance to get back at the Evil Corporate Oligarchy, or whatever she was calling it this week.

Desjardins opened a window on the board: a false-color satcam enhance of open ocean, a multihued plasma of color-coded contours.

"I thought of that," Alice piped up, "but even if you could make out a heatprint against the noise, the circulation's so slow down there—"

"Not temperature," Desjardins interrupted. "Turbidity."

"Even so, the circulation—"

He shot her a look. "Shut up and learn, okay?"

She fell silent, the hurt obvious in her eyes. She'd been walking on eggshells ever since she'd admitted to infecting him.

Desjardins turned back to the board. "There's a lot of variation over time, of course. Everything from whitecaps to squid farts." He tapped an icon; layers of new data superimposed themselves atop the baseline, a translucent parfait. "You'd never get a track with a single snapshot, no matter how fine the rez. I had to look at mean values over a three-month period."

The layers merged. The amorphous plasma disappeared; hard-edged contrails and splotches condensed from that mist.

Desjardins's fingers played across the board. "Now cancel everything that shows up in the NOAA database," —A myriad luminous scars faded into transparency— "Gulf Stream leftovers," —a beaded necklace from Florida to England went dark—"and any listed construction sites or upwells inconsistent with minimum allowable structure size."

A few dozen remaining pockmarks disappeared. The North Atlantic was dark and featureless but for a single bright blemish, positioned almost exactly in its center.

"So that's it," Clarke murmered.

Desjardins shook his head. "We still have to correct for lateral displacement during ascent. Midwater currents and the like." He called forth algorithms: the blemish jiggled to the northwest and stopped.

39°20'14"N 25°16'03"W, said the display.

"Dead northeast of the Atlantis Fracture Zone," Desjardins said. "Lowest vorticity in the whole damn basin."

"You said turbidity." Clarke's reflection, a bright bullseye in its chest, shook its head. "But if there's no vorticity—"

"Bubbles," Alice exclaimed, clueing in.

Desjardins nodded. "You don't build a retirement home for a few thousand people without doing some serious welding. That's gonna generate sagans of waste gas. Hence, turbidity."

Clarke was still skeptical. "We welded at Channer. The pressure crushed the bubbles down to nothing as soon as they formed."