Charlie Chan at the Olympics

The device was stolen by a concealed stowaway on the Hopkins plane. However, Charlie Chan and his son later discovered the stowaway's body, revealing he was murdered after the theft. The true mastermind behind both the theft and the murder was Cartwright, the inventor of the device himself, who orchestrated the crime to profit from selling the invention to international arms dealers.

Earlier in the film, Hopkins mentions that several people knew about the demonstration of the remote control device, suggesting the theft was an inside job.

Lee Chan suspected Yvonne Roland because he observed her behaving suspiciously - he watched her slip a piece of paper into her book and then saw Arthur Hughes retrieve it. Lee also suspected her of being an "adventuress" pursuing financial gain through her connection to the Olympic team, which proved accurate as she was working for the diplomat Zaraka.

When a hotel maid attempted to steal the invention hidden in Betty Adams' candy box, Chan and Inspector Strasser intercepted her. While the maid ran to warn her accomplices through the window, Charlie quietly substituted a harmless book for the device without anyone noticing. This clever switch later allowed Chan to negotiate for Lee's safe release.

Earlier on the train, Chan warned that the device would likely be moved soon, showing he anticipated the theft attempt.

Zaraka, a diplomat working with Yvonne Roland, wanted the remote control device to sell to foreign military interests. The device represented advanced radio control technology that could be weaponized. When Chan revealed he had substituted a book, Zaraka sent him a ticket to the Olympic opening ceremony as part of a larger scheme to force Chan to hand over the actual invention.

Zaraka's men kidnapped Lee Chan to use him as leverage against Charlie Chan. After discovering that Charlie had switched the device with a book, Zaraka orchestrated Lee's kidnapping to force Charlie into exchanging the real device for his son's life. This occurred on the eve of the Olympic opening ceremony when the tension reached its peak.

During the exchange at Zaraka's location, Hopkins was brought in to verify whether the device was authentic. He confirmed it was the real invention, even though Charlie had actually substituted an imitation containing a radio beacon. This deception worked because Hopkins either didn't examine it closely enough or was unaware of the switch, allowing Charlie to successfully negotiate for Lee's release.

Charlie Chan proved that Cartwright was responsible for both the murder of the stowaway in Honolulu and for shooting Hopkins during the confrontation at Zaraka's location. Chan demonstrated that Cartwright had orchestrated the entire scheme - stealing his own invention to sell it to arms dealers, murdering his accomplice when he became a liability, and framing others for the crimes.

Yes, Lee Chan won the 100-meter swimming competition at the 1936 Berlin Olympics. This victory provided a satisfying conclusion to the film, combining the resolution of the mystery with personal triumph for Charlie Chan's family. The win celebrated both Lee's athletic achievement and Charlie's successful detective work in exposing the espionage ring.

Arthur Hughes, despite being an arms dealer, assisted Chan in investigating the device theft because he wanted to recover the invention to sell it himself rather than let competitors profit. Hughes warned Chan about dangers, arranged for the camera to be stolen, and ultimately helped rescue Chan and Lee from Zaraka. His self-interest motivated both his initial cooperation and his later intervention against rival conspirators.

Charlie Chan hid the stolen remote control device inside a candy box belonging to Betty Adams, an Olympic athlete traveling with the team. When Hughes arranged for Adams' camera to be stolen in hopes of finding the device, it wasn't in the camera - Chan had already moved it to the candy box for safekeeping. This hiding spot was discovered by the maid who tried to steal it.