Franklin Dixon's The Vanishing Thieves, 66th book in the "Hardy Boys series," opens with Chet, best friend of protagonists Frank and Joe Hardy, introducing his cousin Vern to Frank and Joe at a diner. Just as the friends leave the diner, they see someone stealing Vern's new car. Though Frank and Joe attempt a chase in their own sports car, they unsuccessfully find the stolen vehicle. Back at the home of the Hardys, they learn that Mr. Hardy is investigating a ring of car thieves. Vern also confides in the family that he is passing through Bayport en route to California, in order to look into the fact that a rare coin he had inherited has mysteriously disappeared. Naturally, Chet and the Hardys volunteer to travel to California with Vern to help with the investigation.
By Chapter 18, Vern's car has been found. The Hardys have also become convinced that Bunker Bank President, Barton Laing, is the thief of Vern's coin. The boys form a plan to trick Laing into meeting with them. Chet phones him, pretending to be a fellow bank president with a son interested in seeing rare coins. They also identify Cylvia Nash as Laing's partner in the theft. Though their plan goes awry, they successfully catch both thieves and find the coin.