Think Fast, Mr. Moto

The film opens with Mr. Moto disguised as a street salesman, engaging passers-by with his goods. During this, he notices a man leaving a shop with a British Flag tattoo on his arm, hinting at potential espionage activities. Moto's attentiveness sparks his interest in the unfolding events.

Inside the shop, Moto observes a wicker basket containing a stuffed body, which indicates a murder has taken place. He quickly uses his mastery of judo to subdue the shopkeeper, uncovering a crime and revealing a dangerous smuggling operation involved in the story.

Moto books a stateroom on a passenger ship heading to Shanghai, signaling the beginning of his journey to investigate the smuggling rings. Onboard, he notices Bob Hitchings Jr., carrying a confidential letter from his father, hinting at a secret mission.

Hitchings befriends Moto and helps him cure a hangover after a casual encounter. The ship stops in Honolulu, where a beautiful woman named Gloria Danton, who is actually Tanya Barova, joins the passengers. Gloria and Hitchings quickly fall in love amid the voyage.

It is revealed that Gloria is a spy working for Nicolas Marloff, involved in smuggling activities. She sends notes to her contact and departs without saying goodbye, arousing suspicion in Moto and Hitchings about her true motives.

Moto discovers a steward searching for Hitchings' confidential letter and confronts him. Using his skills, Moto throws the steward overboard and retrieves the letter, suspecting it's linked to the smuggling operation.

Hitchings arrives in Shanghai and meets with Joseph B. Wilkie, giving him the mysterious letter. However, he later learns that the letter is blank, prompting him to be cautious and suspecting that he's being deceived.

Hitchings, along with Wilkie, Moto, and Lela Liu, searches the International Club, where Gloria is performing. Hitchings discovers Gloria in her dressing room, but their reunion is cut short when Marloff, the club owner and smuggler, catches them together.

Marloff traps Hitchings and Gloria, locking them up to prevent exposure. Moto intervenes by posing as a smuggler to locate them, leading to a showdown. During the confrontation, Lela is shot but manages to reveal Gloria's location to the police.

Wilkie demands Gloria and Hitchings be released, and Moto captures Marloff after a tense chase. Wilkie, revealed to be involved in the smuggling, kills Marloff with the stolen gun, which explodes in the struggle. The police arrive to arrest Wilkie.

With Wilkie's arrest, the smuggling ring is dismantled, and the threats are neutralized. The characters' ordeal concludes as things return to normal, with Moto showcasing his detective skills and justice being served.