Duel in the Jungle

American insurance investigator Scott Walters arrives in London to interview Perry Henderson about a US$2 million policy leaving Perry's elderly mother as sole beneficiary. He meets and is taken with Marian Taylor, Perry's secretary, but struggles to speak with Perry directly. Arthur Henderson explains Perry is deep-sea diving off the coast of Portuguese East Africa, but withholds that he is seeking diamonds on the sea bed. Walters warns Arthur that if Perry continues dangerous activities, the policy could be forfeited.

Walters reads a newspaper headline reporting that Perry Henderson was swept overboard from the SS Nigeria during a storm off Lourenço Marques. Rather than returning to America, Walters resolves to uncover the truth and to locate Marian, who has disappeared. He learns Marian's landlady says she flew off somewhere, hinting at South Africa. With this clue, Walters heads toward African shores to pursue answers.

Walters travels to South Africa to book passage on the coastal tramp SS Nigeria. Learning the ship has already departed, he pivots to Beira to catch it there. Onboard, he shares a compartment with Pitt, an English salesman, while keeping his true purpose secret.

During a storm, Walters and Pitt are the only passengers able to leave their cabin to dine with the ship's captain. He presses the captain about Perry's death while keeping his own occupation secret, which infuriates the captain.

Walters learns that the only witnesses to Perry's death were Perry's firm's employees who also owned the SS Nigeria. He also discovers a secret compartment on the ship and finds a cigarette butt bearing Perry's bespoke markings.

Marian reveals to the captain that she does not want Walters to bother her. Her presence intensifies Walters's suspicion as he continues to dig for the truth.

During another storm, a crewman borrows Walters's trench coat to go outside. A crewman coshes Pitt and attempts to throw him overboard, but Marian's scream stops the assault. Walters deduces the attacker intended to kill Pitt, confusing him for Walters.

Marian goes ashore, and the crew tries to keep Walters on board, but he literally jumps ship. He tracks Marian to Northern Rhodesia, where a safari carries her toward Perry's mother.

With the help of a police superintendent, Walters tracks down Perry's mother. This meeting helps him piece together Perry's whereabouts and the scope of the insurance ruse.

Walters pursues Marian to uncover the truth and they find Perry alive, having faked his death to collect the policy. The revelation heightens the stakes as the pursuers race toward the truth.

Perry tries to kill Walters by giving him a rifle with the firing pin removed so that a lion would do the killing. Vincent, Perry's native right-hand man, kills the lion, escalating the danger and forcing a flight.

The fugitives are pursued by Perry and his African helpers and confront threats from water, gunfire, and wild beasts. They are rescued in the nick of time by the police superintendent, and after a climactic struggle, Perry fights Walters, tumbles into a rapids boat, is saved by Walters, and is arrested. The film ends with Walters and Marian embracing.