One of the best of the Chan series. Keye Luke is hyper as number one son Lee but his occasional annoying outbursts don’t get in the way of the plot as Charlie goes to Berlin after a spy ring and Lee is on the Olympic swim team.
Charlie is going on a fishing trip with his young son Charlie, Jr. At the police station in Honolulu they’re among the many watching the test flight of a remote control plane. It can be taken over from the ground and the pilot can look out the window.
A substitute is flying the plane as the regular one, Dick Masters an Olympic pole vaulter, hurt his shoulder. A spy has snuck on board and kills the pilot and the plane goes missing. When the Chans’ get to their fishing spot they find the plane and the body of the pilot. The guidance system is missing. Charlie discovers some time cards have been altered at the airplane factory and that leads to a mechanic’s hotel room. His body is found in a closet.
The thieves are on a steamship headed for Berlin. Also on board are the Olympic teams. Lee is suspicious of a woman named Yvette Roland. He thinks she’s an adventuress. Yvette is spending time with Dick and his girlfriend Betty Adams, a member of the track team, isn’t happy about it.
Yvette borrows Betty’s camera to take a picture of the team and slips something to a compatriot, Arthur Hughes. Hughes has been trying to buy the robot device from Hopkins. Lee sees it all. Meanwhile, Charlie, Cartwright the inventor of the device and Hopkins (Jonathan Hale), the owner of the plane, all board the Hindenburg and head to Berlin ahead of the ship.
In Berlin, Charlie finds the device in Betty’s luggage disguised as a box of candy. He does a quick switch and substitutes a German-English dictionary. Charlie has the help of Berlin police Captain Strasser who keeps sating, “Things like this cannot happen in Berlin.”
Charlie is closing in on the spy ring when Lee is kidnapped. It looks like he’s headed for failure. But wait………
Interesting that there’s no mention of war clouds on the horizon and the Berlin police couldn’t be more helpful.