A narcotics agent witnesses the death of slaves at sea and investigates a narcotics ring that takes him to Shanghai, Cairo, Beirut, Havana, and New York.
Off San Francisco in 1935 Michael Barrows (Dick Powell) chases a freighter outside the 12-mile limit and sees it dump a hundred men in the sea. Barrows goes to Shanghai to find the captain, and the Chinese narcotics commissioner Lum Li Chow (Vladimir Sokoloff) suggests a Japanese runner. Barrows is led to Nicholas Sokim (Ludwig Donath), who has a narcotics past. Barrows identifies Shannon as a smuggler and goes on his tour. Barrows talks with Ann Grant (Signe Hasso) and Shu Pan Wu (Maylia). Shannon returns Barrows' lost notebook and knocks him out. He wakes in a boat, and Grieg says that Shannon was killed to protect him. Barrows suspects Sokim and goes to see Shu Pan. Ann says they will be questioned. Police raid Sokim's garage, and Li Chow shows Barrows Sokim's refining equipment. Sokim poisons himself to avoid talking. Li Chow says that Barrows alerted Sokim and asks him to go to Egypt. Ann says she is going to San Francisco with Shu Pan, but Li Chow learns Ann was in Egypt.
Barrows flies to Cairo and confers with narcotics commissioners Amar Hassam (Lou Krugman) and the British Hadley (Vernon Steele). At night they climb a cliff to a rose farm, and Barrows finds a poppy stem. They find a hundred slaves sleeping. The owner Binda Sha (Fritz Lieber) confronts them. When Hadley shows they are surrounded, Binda Sha jumps off the cliff. They try to follow the opium.
They fly to Beirut and reach the camel herd at night. They detect packages of opium in the stomachs of the camels, and they have the bales of camel hair followed.
Barrows learns that Ann is going to Havana, and he takes a ship to Cuba. There he persuades the Cuban commissioner Berado (Luis Van Rooten) to let it be refined and shipped out. Barrows watches the bail go to Naftalie Vrandstadter (Ivan Triesault), who is with Ann. They are sailing to New York. Barrows observes three cartons marked "Butter" put aboard in the kitchen.
On board Barrows sends a coded message to his boss. Vrandstadter finds Barrows in a vacant cabin and comes back later with Ann. The next day they approach New York. During a fire in the kitchen the opium is moved to trash cans. Vrandstadter, Ann, and Shu Pan watch the cans being dumped at sea while Barrows is knocked out. He recovers and has the galley searched, asking about the garbage cans and the fire. Barrows accuses Ann and finds that Vrandstadter shot himself. They figure where the stuff was dumped and go in boats. With shooting they capture the boat with the narcotics. Shu Pan grabs a gun, orders where the boat is to go, and admits she is Japanese. She shoots Barrows; but they are blanks, and she is captured.
This detailed docudrama emphasizes that international
cooperation between anti-narcotics law enforcement agencies can
help to track down the rings of smugglers.