They continued sweeping through the grid, but rather than solve the underwater mystery they only added to it. A second line soon appeared, and then a third, all aligned in a converging angle to the north. Working their way through several more search lanes, they reached the conjunction. Like a giant seven-fi ngered hand lying on the bottom, the sonar revealed four additional lines that joined the others in a mass convergence. Piecing the images together, they could see that the lines all fanned out for approximately fifty yards, then ended abruptly. A single, heavier line extended north from the conjunction, running parallel to the shoreline. The sonar was able to track it for a short distance before it suddenly disappeared into the sediment close to shore. When they reached the end of the search grid, Dirk stopped the motor, then pulled in the sonar fish with Trevor’s assistance.

“It’s nearly seven,” Summer said. “We need to head back within the hour if we want to avoid running up the channel in the dark.”

“Plenty of time for a quick dive,” Dirk replied. “Might be our only chance.”

There was no argument from the others. Dirk slipped into a dry suit as Summer repositioned the boat over a marked spot where the seven lines had converged.

“Depth is ninety-fi ve feet,” she said. “Be aware there is a large vessel on the radar headed our way, about fifteen miles to the north.” She turned to Trevor and asked, “I thought you said there’s no midweek cruise line traffic through here?”

Trevor gave her a confused look. “That has been my experience. They follow the schedules pretty tight. Must be a wayward freighter.”

Dirk poked his head in and eyed the radar screen. “I’ll have time for a good look before she gets too close.”

Summer turned the boat into the current while Trevor tossed an anchor off the bow and secured their position. Dirk adjusted his tank and weight belt, then stepped over the side.

He hit the water at nearly slack tide and was relieved to find the current minimal. Swimming toward the boat’s bow, he wrapped his fingers around the anchor line, then kicked to the bottom.

The cold green water gradually swallowed the surface light, forcing him to flick on a small headlamp strapped over his hood. A brown stony bottom dotted with urchins and starfish materialized out of the gloom, and he confirmed the depth at ninety-three feet as he adjusted his buoyancy. He let go of the anchor line and swam a wide circle around it until he found the object observed by the sonar.