Charlie Chan in Rio

Detective Charlie Chan travels to Rio de Janeiro with his son Jimmy and Chief Souto to arrest Lola Dean on suspicion of a Honolulu murder. They prepare their case around Lola's public persona and her recent engagement, hoping to confront her directly. The trip sets the investigation in motion in a foreign setting.

Following Lola's performance, Carlos asks Lola to marry him and she accepts, creating potential motives rooted in jealousy and control. The romance complicates the case for Chan as new stakes emerge. The engagement becomes a catalyst for the ensuing events.

Lola goes to see Marana, the Hindu psychic, who places her in a semi‑conscious state using an infusion of coffee and herbed cigarettes. In that trance, Lola confesses that she killed Manuel Cardozo in Honolulu after he refused to marry her. The psychic records the conversation for later use.

On the way home from the psychic visit, Lola convinces Carlos to elope rather than marry later, seeking a furtive future away from her past. The idea of escape adds urgency to the looming investigation. Lola begins packing as preparations begin in earnest.

Chan, Jimmy, and Chief Souto arrive at Lola's house to arrest her, only to discover Lola dead in her room. They conclude she was murdered and note several clues deliberately left to misdirect them. Lola's jewelry has gone missing, deepening the mystery.

Paul Wagner is brought into the case and admits he was Lola's husband, though they had separated. This revelation hints at possible motives tied to Lola's past relationships. The investigators begin to map Lola's social circle for further connections.

The man who posed as Lola's psychic is revealed to be Alfredo Cardozo, the brother of Manuel Cardozo. This links Lola's supposed confession to a real family motive and expands the circle of possible culprits. The discovery adds a dangerous layer to the case.

Jimmy witnesses a hushed exchange between Lola's butler Rice and maid Lilly. Rice pressures Lilly to stay quiet about something he saw earlier, suggesting a cover-up within Lola's household. The overheard conversation becomes a critical lead for the investigation.

Chan discovers scratch marks under the floor and suspects they were made by Lola's brooch, with a pin possibly still stuck in the murderer's shoe. He also finds similar marks beneath a chair at the dinner table, tying them to the alleged killer's position. The clues shift attention to locations around the guests.

Jimmy finds Lola's jewelry in Rice's room and confronts him, but Rice insists he did not kill Lola. During the investigation, the lights go out and Rice is shot, complicating the case and elevating tension among the witnesses. The blackout creates a dramatic pivot point in the pursuit of the killer.

Chan reveals scratch marks under Helen's chair at the dinner scene, suggesting she played a role in the crime. Helen protests her innocence, and Chan hints that Alfredo Cardozo’s method could have framed her. The investigation tightens around those seated at the table.

Alfredo Cardozo makes a move to confess, but Helen stops him and discloses that she is the true killer. She explains Lola's plan to elope and the motive to protect her own past, revealing the real sequence of events. The confrontation shifts blame away from Cardozo and toward Helen.

Helen reveals she killed Lola to prevent exposure of her marriage to Manuel Cardozo and Lola's imminent elopement. She admits dosing and silencing Lola's associates, including manipulating Rice with jewels to keep him quiet, and later shooting him when he discovered too much. The confession ties together the motives and means.

Chief Souto arrests Helen and takes her to jail, bringing the case to a close. Chan reflects on the case while informing Jimmy of his upcoming U.S. Army draft, providing a somber epilogue. The film ends with justice served but personal futures unsettled.