The Three Investigators in The Secret of Terror Castle by Florian Baxmeyer

6.30

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.