Austin climbed down from the submersible onto the deck of the Mummichug. The twin-hulled, eighty-foot craft was the smallest NUMA research vessel he had ever worked on. Like the tiny fish that was its namesake, the Mummichug was at home in fresh or salt water. It was a modified version of a vessel designed for inshore duty in the cantankerous waters along the New England coast.

It was seaworthy and fast, driven by powerful diesel engines that gave it a cruising speed of 20 knots. It slept eight and was ideal for short missions. Despite its size, the Mummichug?" winches and A-frame could haul heavy loads. And a larger vessel would not have been able to navigate the winding river to the glacier.

Finding himself at loose ends without Skye to talk to, Austin grabbed a mug of coffee in the galley, and then went below to the remote sensing lab. It was a small space crammed with several computer monitors set up on tables. Like everything else on the ship, the lab was understated, although electronic nerves and ganglions connected the monitors to a sophisticated array of sensing instruments.

He plunked himself down in a chair in front of a screen, took a sip of coffee and called up the file on the side-scan sonar display. Dr. Harold Edgerton had pioneered side scan sonar in 1963 when he'd mounted a sonar transducer on the side rather than the bottom of his survey boat. The discovery, which allowed surface vessels to cover large areas of bottom, would revolutionize underwater search techniques.

When the Mummichug had first arrived on site, Skye had asked for a survey along the shore across the lake from the glacier, which would have presented a formidable roadblock to caravans. She reasoned that travelers would have lingered near the river before fording it and a settlement might have built up nearby. The waterway itself may have been used as a tributary of the Amber Route.

While the submersible had carried out its underwater mission, the ship had continued its sonar survey along the lake's perimeter. Austin wanted to see what the scan had picked up. He put the screen in a slow scroll and the high-resolution sonar image flowed down from the top of the monitor like twin amber waterfalls. Displayed on the right side of the screen were latitude, longitude and position.

Interpreting sonar images requires a practiced eye, but it is not the most exciting occupation. With its flat, gravelly bottom, Lac du Dormeur was even more monotonous than some. Austin found his thoughts drifting off. His eyelids had dropped to half-mast, but they snapped open when an anomaly caught his attention. He scrolled back, leaned forward to examine the dark cross etched against the monotone background, then, with a click of the computer mouse, zoomed in on the image and enhanced the details.