A crewman named Evans is very distressed after receiving notification that his wife’s pregnancy has entered complications. Upon his commanding officer, Bishop, refusing to allow him emergency leave, they get into a fight and Evans knocks out Bishop. Unfortunately crewman Blake leaves his sonar post to break up the fight, which, unknown to him, had started going off, due to a derelict mine field being detected. The mines are not spotted until the Seaview is right on top of them, which, once Admiral Harriman Nelson orders the sub to reverse course, it ensnares itself in a mine.