William Castle brings his usual bag of entertaining tricks to this cult favorite about a doctor who finds himself at the remote castle home of an old flame -- whose sadistic husband's ever-present smile hides a sinister secret. Castle's gimmick for this film consisted of an introduction prior to the credits and then a reappearance at the conclusion in which he asked audiences to vote (thumbs up or thumbs down) as to whether or not the evil Sardonicus should be dealt further punishment. Only one ending was filmed, but the deserving finish for the bad guy was a perfect topper. Mr. Sardonicus is by no means a great picture, but a strong argument can be made for it as one of Castle's better works. For most critics, that's not saying much, but Castle never failed to deliver the goods and Sardonicus is no exception. The tale plays like an extended Twilight Zone episode, building up the suspense through the character of Sardonicus, who isn't actually seen until nearly halfway through the film. Then the suspense shifts over to the terror of what lies behind his emotionless mask. The payoff is a shockingly good one when the character's true face finally hits the screen with a disturbing makeup job kept to a minimum to leave the horror more in the viewer's mind. What the film really could have used is a headline actor. Guy Rolfe is watchable in the role of Sardonicus, but Vincent Price or Christopher Lee could have added immeasurable life to it. Ronald Lewis and Audrey Dalton are simply wooden while Oscar Homolka recalls Bela Lugosi in his Ed Wood years.