This late-period William Castle thriller never hits the feverish heights of The Tingler or Homicidal but offers a few quirky delights for the patient viewer. The script's unusual combination of sub-Hitchcock thriller theatrics and Father Knows Best-styled moralizing never quite hits the fever pitch necessary for a top-notch thriller but is oddly compelling enough to keep the viewer involved. The performances are decent but lack the spark that would have enlivened the story: Sarah Lane and Andi Garrett are competent but not terribly charismatic as the teen heroines and John Ireland underplays his murderer role in a way that keeps it from being as menacing as it could have been. The one really memorable performance comes from Joan Crawford, who tears into her supporting role with a scenery-devouring vigor that is fun to watch. On the plus side, I Saw What You Did benefits from slick technical credits: Joseph Biroc's sharp black-and-white cinematography adds some much-needed atmosphere to the story and Van Alexander's swinging, Henry Mancini-esque score brings a certain period charm to the film. However, the best element of I Saw What You Did is William Castle's direction: He creates an inspired variation on Psycho's shower scene early in the film and creates a memorably spooky and intense finale in an isolated suburban home. In the end, I Saw What You Did is one of the lesser entries in the William Castle filmography but Joan Crawford's performance and a few flashes of Castle's campy showmanship make it worth a look for kitsch aficionados.
