This delightful gimmick film from producer-director William Castle stars Vincent Price as Dr. Chapin, a scientist who discovers a caterpillarlike parasite that grows in the human spine when someone is afraid and that, unless they scream, can grow large enough to kill them. He solemnly dubs this creature the tingler. Philip Coolidge plays the owner of a nearby cinema who befriends the doctor and whose deaf-mute wife suddenly receives all sorts of shocks, like the sight of a bathtub full of blood with a hand reaching out from it. Since she can't scream, she dies, and Chapin gets his hands on her oversize tingler. When it eventually escapes inside the movie theater, the film within the film, and then the film itself, stops for an announcement from Price, out of character, urging the audience to scream their heads off. Castle originally had random seats in theaters equipped to deliver small electric shocks at this key moment, and he hired women to faint and ushers to carry them out, all in his determination to get the audience to scream. Even without all the ballyhoo it's a fun film, a delightful relic from the days of the gimmick.