Overview:In June 1942, Japanese bombers tried to level the American presence on Midway Island in a bid to steam unimpeded toward the U.S. mainland. Yet the U.S. Navy had two aces up its sleeve: advance knowledge of Japanese plans and a dive-bomber that was nearly invulnerable to attack. When the smoke cleared after the U.S. ambush, four Japanese aircraft carriers -- the Kaga, the Soryu, the Hiryu and the Akagi -- lay on the ocean floor. The program shows how the U.S. Navy and private enterprise teamed up on a 1999 expedition that solved a half-century of military mystery: where exactly did the Japanese ships go down?