May 7, 1915, the passenger ship Lusitania was en route home when a German sub blew it out of the water, killing more than 1,000 men, women and children. The sinking of this great ocean liner shocked the world, and "Avenge the Lusitania!" was the rallying cry that lured many young American men to enlist during World War I. In this dramatic 85-minute special, Discovery Channel brings you the story of the doomed ship and, for the first time, goes inside the cramped, foul-smelling hull of the U-boat that fired the fateful torpedo.