Other editions of book What Happened at Midnight

Books 10, 11, & 12 of the thrilling adventures of America's favorite detective duo, Frank and Joe Hardy. #10 - Joe Hardy is kidnapped by a gang of jewel smugglers as a warning for the Hardy Boys' father to stay away from their operation. #11 - A banker asks the Hardy Boys to solve the mystery of a secret room in an old deserted mansion. #12 - Frank and Joe attempt to foil a ruthless espionage ring in their effort to sabotage the United States space program.

Frank and Joe Hardy receive an unusual assignment from their detective father. They are to "break into" the house of a Bayport neighbor, Malcolm Wright, and retrieve a top-secret invention that the scientist had hidden in his study before leaving for California. The invention is in danger of being stolen and the boys race against time to beat the thieves at their own game. The young detectives soon discover that they are involved in a mystery far greater in scope than just retrieving the invention.