Among the passengers on board the Australia-bound S.S. Bombay is Merrill Hammond, the governor of the penal island of Caruba, and Diana Bryce, who is meeting her brother in Australia. After the ship is bombed by the Japanese and sent to Caruba, Hammond invites Diana to spend a week with him on the island, and she agrees. The other residents of the island include the alcoholic prison doctor, Doc Brown, and George Kent, one of the administrators. Hammond shows Diana to a house that, he explains, he built for his wife, who died shortly after her arrival. Kent, a harsh disciplinarian, is displeased when he learns that Diana will be staying on the island. Later, Brown informs Hammond that an epidemic of typhus has hit the island. Kent, Brown and Hammond all dine with Diana, who expresses a desire to visit the prisoners. While they are eating, convicted murderer Dan Curtis watches them through a window and is discovered by Kent. He is reprimanded and returned to his room. Later that night, Curtis meets Diana, who is his wife, and she explains that she has come to the island to help him. While they are talking, Kent, who has heard their voices, investigates, but Diana is able to avert a search when Hammond stops by to drop off a book. After they leave, Curtis tells Diana that he plans to escape on a supply ship. She begs him to wait for a new trial but when he refuses, gives him money and jewels. Meanwhile, Kent examines Curtis' records. Later, Curtis is found with Diana's jewels and Kent suspects the truth. Curtis is confined to solitary, and realizing that this makes it impossible for him to escape, Diana then secretly tells Brown the truth. She begs him to declare Curtis dead from typhus so that he can safely escape. Brown agrees, but while he is out of the room, Diana sees Curtis' record and learns that he is a bigamist. Curtis' "body" is carried to the ship, where he awakens. Diana pays Brown, but then tells Curtis that she is no longer in love with him. On the island, Brown confesses his deed to Hammond, who does not believe him. The ship is grounded by fog, and in the morning, Hammond questions the captain, but believing that Diana is still in love with Curtis, lets him escape. When Kent challenges Hammond, he resigns in his favor. Curtis is killed in a shipboard struggle, and Diana returns to the island in search of Hammond, with whom she is now in love. When she learns that Hammond has quit, she hurries after him, and they leave the island together.