The preparation for the Battle of the Coral Sea is the basis of this wartime drama. A submarine captained by Jeff Conway (Cliff Robertson) successfully scouts the location of enemy installations, ships, and subs and then starts to head back to friendly waters. Before chugging very far in that direction, the submarine is spotted and captured by the Japanese. The crew members are taken prisoner by an even-handed Commander Mori (Teru Shimada) and held on the Japanese forces' island base. While chaffing under a ticking clock as the day of the final confrontation draws near, an island woman is secretly enlisted to help smuggle out three of the prisoners. If they can make it off the island to their own base, then the all-important information on the Japanese positions will tip the scales in favor of the U.S. Navy.