The Vanishing Thieves
Franklin W. Dixon
 Chet Morton's cousin, Vern, is on his way to California to find a rare and valuable coin mysteriously missing from his uncle's bank vault. When he stops in Bayport, his brand-new car is stolen. The Hardys take on a double mystery-and double danger as they head for the West Coast to investigate this sinister mystery.this is what the back of the book says.