Despite the danger--or perhaps because of it--this yearly trip to Zanzibar was one of their favorites. Along with sharks, prey fish, rip currents, and underwater sandstorms that lasted for months, the EACC offered up treasure--albeit usually bits and pieces worth nothing more than their curiosity factor, but this was enough for Sam and Remi. Over the centuries, ships had been plying Africa's east coast from Mombasa to Dar es Salaam, many of them laden with gold and gems and ivory bound for colonial empire cities. Countless ships had sunk in and around the Zanzibar Channel, the contents of their holds spilled along the bottom, just waiting for the right current to uncover or move them within reach of curious divers such as the Fargos. Over the years they'd recovered gold and silver coins from the Roman Empire to Spain, Chinese ceramics, Sri Lankan jade, silverware . . . From the fascinating to the mundane, they'd uncovered it. So far on this trip, they'd found only one item of note: a diamond-shaped gold coin so barnacle-encrusted they could make out no details.

Sam and Remi watched the sharks feed for a few more minutes and then, by mutual nod, turned and began finning south along the bottom, each stopping occasionally to use a Ping-Pong paddle to waft at the sand, hoping the lump that had caught the eye might be a hidden bit of history.

Chumbe Island, roughly six miles long and two miles wide, is shaped like a woman's boot, with the shin, ankle, and forefoot facing the channel, and the back of the calf, the stiletto heel, and sole facing Zanzibar proper. Just above the ankle there was a break in the sandbar, an inlet that led to the lagoon created by the stiletto heel.

After fifteen minutes of trolling along the sand, Sam and Remi reached this stiletto break, then turned west until they were ten yards off the beach, then swung north again to resume their search. Now they became more watchful. It was along this stretch of the sandbar that the main channel pushed dangerously close to the beach, a bubble-shaped salient that narrowed their Safe Zone to a mere forty feet. Remi swam inshore and ahead of Sam by a few feet, each of them frequently checking to make sure the other hadn't drifted toward the precipice.

In the corner of Sam's right eye he saw a glint, a fleeting flash of gold. He stopped swimming, settled knees first into the sand, then tapped his dive knife on his tank to get Remi's attention. She stopped swimming, turned, and finned back to him. He pointed toward the spot. She nodded. With Sam in the lead, they swam toward shore until the sandbanks came into view. A wall of sand nearly twelve feet tall, these banks marked a precipice of sorts where the water depth dropped from chest height to twenty feet. They stopped before the bank and looked around.

Remi shrugged Where?