The Secret of Terror Castle is an American juvenile detective novel written by Robert Arthur, Jr.[1] It is the first book in the "Three Investigators" series.

Three boys are investigating a known haunted house, Terror Castle, in hopes that perhaps the film director Alfred Hitchcock would use it in his upcoming movie.

They briefly gain an audience with the skeptical Hitchcock, who is dismissive but agrees to introduce their case if they are able to demonstrate that the castle is truly haunted.

Terror Castle is the former home of movie actor Stephen Terrill, who died in a possibly suicidal car accident that occurred as his career was on the verge of collapse.

During their investigations, the boys find very scary and seemingly real activities going on in the abandoned structure, such as the Fog of Fear and the Blue Phantom.