Charlie Chan's old friend from Arizona thinks that someone is trying to kill him. Chan travels to the friend's dude ranch and digs into the mystery, which he quickly discovers is tied up with a nearby gold mine.
Roland Winters is solid if unexciting as the famous detective in this passable series entry. Victor Sen Young and Mantan Moreland are featured in sizable roles this time around; as number two son Tommy and chauffeur Birmingham Brown, they liven up their portions of an otherwise rather bland production.
Tim Ryan attempts to add color as a tipsy ranch guest whom Chan quickly recognizes as his friend Lieutenant Mike from San Francisco. Lieutenant Mike, it turns out, is undercover at the ranch and investigating the same funny business at the mine.
Other story elements include a smuggling ring, a suspicious mine shaft accident, a miner's shack with a trap door in the floor leading to a secret tunnel.... It really doesn't make much sense but it's mildly entertaining.