The three detectives are his young friends Bob Andrews, Pete Crenshaw and Jupiter Jones. They live in a town near Hollywood. Their stronghold is a salvage warehouse, their headquarters is an old caravan in which they have equipped a crime laboratory. Their agency "Three Detectives" reveals any secrets, riddles and puzzles. Friends-detectives boldly take on the most important and complicated cases and bring them to the end with honor.

Three detectives and a poltergeist Creepy things happen in Mrs. Cartier's house: knocks are heard, furniture moves, cups fly through the air. This kind of thing is just the taste of Justus, Peter and Bob! But the detectives' initial enthusiasm soon turns into fear and horror. Was there really a poltergeist there? Could it be Mrs. Cartier's late husband trying to contact her? A natural explanation for these phenomena is excluded. And even Justus, usually so cold-blooded, suddenly doubted his own sanity...