The Three Investigators in The Secret of Terror Castle
The Three Investigators in The Secret of Terror Castle streams in the US free with ads on Tubi TV, as of October 6, 2026.
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.
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