In swinging London, a group of twenty-something friends are attending a rather dull party, and they decide to gather for kicks at an old, supposedly haunted mansion where one of their number used to play as a child.

Among the group is American ringleader Chris, his bored girlfriend Sheila, promiscuous Sylvia (who has her eye on handsome two-timing Gary) and his "good girl" date, Dorothy.

Also tagging along are nervous, heavy-set Madge, her sarcastic, hot-tempered boyfriend Peter, sweet-faced Richard and his friend Henry.

While Sheila is out of the room, Richard recounts how he was locked in a basement for three days as a child and tells that he has a paralyzing fear of the dark.

Just as Richard is about to strike, the moon goes behind a cloud, bringing about his reversion to childhood and fear of the dark, thus saving Sheila as the police arrive.

[3] He rewrote the script in 1967, "further developing its darker psycho-sexual themes and sharpening characters and dialogue to reflect the current cynical underbelly beneath the superficial Sixties culture."

[4] Exterior scenes were shot at Bank Hall in Bretherton and the Birkdale Palace Hotel, Southport; other locations included Carnaby Street, London and Grim's Dyke, Harrow.

"[13] Kevin Thomas of the Los Angeles Times reviewed the film jointly with The Crimson Cult and found them both to be "enjoyable British horror pictures ... that transcend their formula plots through exceptional scripting, efficient direction and intelligent performances.

"[14] The Monthly Film Bulletin wrote that the story "strains credulity even for a thriller and is elongated to breaking point," concluding, "The shock sequences are reasonably well contrived and there is a liberal flow of blood, but this haunted house is more likely to induce sleep than nightmare.

"[15] Filmink wrote "Avalon’s casting doesn’t work – too American, too old, too broad – but the movie does have a cult and some interesting touches.