“Now I know what it feels like to be a canned sardine,” he said. “Thanks for the rescue, Kurt. I can’t believe the cable broke.”

“It didn’t break,” Zavala said. “Kurt says that it was cut.”

“Cut?” Kane’s lower jaw dropped open. “I don’t understand.”

Austin showed Kane the video of the AUV, and said, “Can you think of anyone who would go through all this trouble to put the bathysphere on the bottom?”

Kane shook his head. “Nope. What about you?”

“Joe and I are as much in the dark as you are,” Austin said. “There’s no reason we can think of to scuttle a scientific and educational project.”

Gannon’s voice came over the ship’s intercom.

“Call coming in for Dr. Kane,” the captain said. “Can he take it?”

Austin plucked the intercom’s receiver from the wall and handed it to Kane.

Kane listened to someone on the line, and said, “That’s impossible! . . . Yes, of course . . . I’ll be ready.”

When Kane had clicked off, Austin asked, “Is everything all right?”

“Not really,” Kane said. His face had turned the color of cold ashes. “If you’ll excuse me, I’ve got to talk to the captain.”

Kane asked the medic to help him get to the bridge.

Austin stared at the door for a moment, then shrugged and said to Zavala, “Come to the machine shop with me. I’ve got something to show you.”

The mandible Austin had wrested from the AUV had been wrapped in cloth and clamped in a padded bench vise. Using a set of thick work gloves, he removed the blade from the vise. It was about four feet long and six inches wide, curved along the inner edge and tapering to a point. He found the metal surprisingly light, and he estimated its weight at less then twenty pounds.

Zavala whistled softly. “Beautiful,” he murmured, “a metal alloy of some kind. Whoever built it didn’t expect it to be twisted where it joined the AUV. That was the weak spot. The edge on this thing is as sharp as a samurai sword.”

“You can see how a pair of these butter knives could ruin your day.”

“Too bad Beebe isn’t around,” Zavala said. “It might change his mind about the dangers of the deep ocean being exaggerated.”

“The ocean didn’t produce this thing. It’s decidedly man-made.” Austin carefully turned it over. The metal had been perfectly forged except for a single flaw the size of a pinhead a few inches from where the blade had snapped off the AUV.

Austin rewrapped the blade and clamped it back in the vise.

“You spent quality time with Doc . . . Did he say anything that might shed some light on this mystery?”