What Happened at Midnight is the 10th book in the Hardy Boys series, where Frank and Joe Hardy must retrieve a secret invention from a neighbor's house before thieves do, leading them into a larger case involving jewel thieves and smugglers, a kidnapping, and a dangerous chase that culminates in a stormy night on Barmet Bay. The mystery involves a dangerous gang, a kidnapped Joe, and a race against time to stop smugglers, with the title referring to a key moment when Joe disappears at midnight.
