During World War II, the USS Indianapolis is deployed on a top-secret mission to deliver parts of an atomic bomb set to be used in the Hiroshima bombing. The mission is successfully completed, but on its return journey, the ship is torpedoed by a Japanese submarine. The ship sinks rapidly, leaving around 900 crew members stranded in shark-infested waters without lifeboats or adequate supplies. Faced with dehydration, exposure, saltwater poisoning, and continuous shark attacks, the survivors struggle to stay alive and maintain hope while awaiting rescue.

Amidst the chaos, Captain McVay grapples with his sense of duty and responsibility as he faces both the elements and the threats from within his own ranks. The harrowing ordeal pushes the men to their physical and psychological limits, testing their bravery and comradeship. The story focuses on their relentless fight for survival and highlights themes of heroism and sacrifice in the face of seemingly insurmountable odds. As days pass, the survivors grow increasingly desperate, but their spirit and tenacity shine through as they cling to life and await a miracle.