On May 7, 1915, the RMS Lusitania, jewel of the Cunard Line, was on a New York-to-Liverpool run when it was attacked by a German U-boat 12 miles off the coast of Ireland. At 2:10 p.m., a torpedo plowed into the ship and exploded. Fifteen seconds later, a massive second explosion rocked the ship again. Within a mere 18 minutes, the Lusitania plunged 300 feet to the bottom of the Celtic Sea. Of the 1,959 passengers and crew, 1,198 were lost. The tragedy sparked anti-German fervor that eventually drew the United States into World War I. [Colin] Barnes has had a long career as a fisherman and dive boat captain. He's sailed over the wreck of the Lusitania at least 50 times. He often reflects on what it must have been like during the disaster - more than 1,000 people in the freezing water, wreckage strewn about. Everyone who survived said how awful it was, listening to all these people crying for help," he muses. "Just hundreds of people were about to perish in the cold water and just yelling for help." His voice quavers slightly as he recounts the unfathomable actions of the British Royal Navy. The Navy had dispatched a cruiser from nearby Queenstown to undertake a rescue - but the ship was mysteriously recalled just as it steamed into view of the survivors. The stricken masses were left frantically waving in disbelief. With its historical intrigue and forensic cul-de-sacs, the Lusitania is a powerful magnet for a colorful cast of obsessives determined to solve the mystery.