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.

The Mystery of the Nervous Lion Alfred Hitchcock asks Jupe, Bob and Pete to find out why a lion in a local amusement park suddenly began to behave very strange.