“I'm getting a side current that could make things tricky, but I'll see what I can do.” Gunn maneuvered the vehicle left and right, then when it was directly centered, he put it through the hole as easily as a seamstress threading a needIe. The ROV was capable of turning within its own radius, and Gunn executed a three-hundred-sixty-degree turn. The camera captured slimy gray piles of debris. Gunn probed a corner with the ROV's manipulator, stirring up a powdery cloud of rust. Then the ROV got tangled and wouldn't, move. Gunn waited for the dust to settle and wriggled the ROV until it broke free of the overhead wire that had snagged a projection of its protective shielding.

“What do you think?” Gunn said, turning to Austin.

“I think anything of value has been removed. We'll have to piece together the story from the ship itself, not what's in it.” He pointed to a wall shelf. “What's that?”

Austin's sharp eye had caught a dark, squarish object. Gunn used the manipulator to clear away a pile of amorphous grayish-brown trash and made several fruitless attempts to grab the object. It kept slipping away like a prize in a penny-arcade game. Gunn set his jaw in determination and pushed the object into a corner where he could get a firm grasp on it, then he backed the ROV out of the cabin and moved the manipulator to put the prize directly in front of the lights. The claw clutched a small, flat box.

“I'm bringing her up,” he said. He reversed the ROV's direction and sent the vehicle scuttling back to the Argo. Minutes later, the lights of the moon pool appeared on the screen. The captain ordered the ROV's handlers to stabilize the artifact in seawater and send it to the vehicle control room. Soon a technician arrived, carrying a white plastic bucket. Gamay, whose background in nautical archaeology made her the most experienced conservator on board, asked for a soft brush. She removed the box from the bucket and gently placed it on the floor. Then, with soft strokes, she brushed a thumbnail patch of the black patina to reveal the gleam of metal.

“It's made of silver,” she said, and continued to work until fifty percent of the top was cleaned. The metal was embossed with a double-headed eagle. Gamay examined the clasp. “I might be able to get this open, but I don't dare because I could destroy what's inside when it hits air. It may need intense conservation.” She glanced at the captain.

“The Argo is primarily set up for biological and geological survey,” Atwood said. “There's another NUMA ship called the Sea Hunter doing archaeological work not far from here. They might be able to help.”

“I'm sure they can. I did some research on the Sea Hunter a couple of years ago,” Austin said. “She's the sister ship of the Argo, isn't she?”

“That's right. The two vessels are almost identical.”