Three Investigators in the Secret of Terror Castle

In a house that seems to have a life of its own, the young detectives must outwit a clever and evil "ghost."

Clowns are usually the last people you'd suspect of committing crimes, so Jupiter, Pete and Bob - The Three Investigators - hardly pay attention when a one sneaks into Jupiter's birthday party and tries to make off with something. Though they don't catch the clown, they retrieve his booty: it's a tape of Jupiter's parents, who died several years earlier. They were also investigators, and on the trail of something big... The only clue they have is the name Stephen Terrill, a once-famous inventor who lived in what is now called "Terror Castle." An apt name, as it soon turns out! Fearlessly defying the mysterious machines that seem to make the house itself come alive, they penetrate to the secret heart of Terror Castle and come upon Stephen Terrill's invention: a diamond-making machine! But there's no time to admire the stones, for the ghost of Stephen Terrill appears - and he doesn't like intruders...