The hobby detectives “The Three Investigators” want to take a little break. So they take advantage of an offer from Peter's father, who has accepted a job in South Africa and wants to take the detectives there. But Jupiter, Peter and Bob wouldn't be the three investigators marks feared by the criminal world if they just lounged around in the sun on their vacation. So it's no wonder that the clever boys soon have their next case to solve...

A new case for the cult detectives! Not by coincidence, a mysterious videotape falls into the hands of Jupiter Jones, Pete Crenshaw and Bob Andrews during Jupiter's birthday party in Rocky Beach. On it is a recording of Jupiter's long dead parents. In their message they want to communicate to their son the key to an especially tricky riddle.

A small group of teenagers are trapped in a deserted movie theater and stalked by a crazed B-movie actress out to kill for the demise of her career.