Who kills the man that gets buried at sea?
On Christmas Eve, the submarine USS Copperfin, under the command of Captain Cassidy, departs San Francisco on a secret mission. At sea, Cassidy opens his sealed orders, which direct him to proceed first to the Aleutian Islands to pick up meteorologist Lt. Raymond, then to Tokyo Bay to obtain vital weather intelligence for the upcoming Doolittle Raid.
On the way, two Japanese planes attack; both are shot down, but one pilot manages to parachute into the water. When Mike goes to pick him up, he is stabbed to death. New recruit Tommy Adams shoots the pilot, but because he was slow to react, Tommy blames himself for Mike's death and volunteers to defuse an unexploded bomb stuck under the deck. When Mike is buried at sea, Greek-American "Tin Can" (Dane Clark) does not attend the service, which angers the other men until he explains that every Allied death causes him great pain.  Meanwhile, Raymond, who lived in Japan, discusses how the Japanese people were led into the war by the military faction.
As the submarine nears Tokyo Bay, the Copperfin has to negotiate its way through protective minefields and anti-torpedo nets. When a Japanese ship enters the bay, Cassidy follows in its wake. That night, a small party, including the ship's womanizer, "Wolf" (John Garfield), goes ashore to make weather observations. Meanwhile, Tommy is diagnosed with  appendicitis. "Pills", the pharmacist's mate, has to operate following instructions from a book, using improvised instruments, and without sufficient ether to last throughout the procedure.  The operation is a success, and "Cookie" Wainwright begins to prepare the pumpkin pie he had promised to bake for Tommy.
the pilot