William Castle directs this thriller about a couple of teenage girls that make crank calls. They call random people from the phone book and say "I saw what you did and I know who you are." Unfortunately for them, one number they call is the house of a murderer. The murder occurs when they are on the phone, but they have no idea.
John Ireland plays the murderer and when he gets this call, he freaks out. He thinks his murder has been witnessed. The girls are curious about this man they have called. They think he sounds sexy. They decide to drive by his house to catch a quick glimpse of him. Unfortunately, they are caught by Ireland's girlfriend played by Joan Crawford. She takes the registration from the girl's car, which belongs to her parents. The kids then drive home embarrassed of what had happened.
Ireland then takes the registration, which has the teen's address on it and he pays a visit to them. To save himself from life imprisonment, Ireland tries to kill the teenage girls. When it looks like lights out for the lead girl, the cops come and save the day.
While William Castle is famous for his horror films, he is most famous for his gimmicks. The gimmick for "I Saw What You Did" involved seat belts that were installed in several movie theater seats. Castle publicized the film as such a thriller that you audiences needed to be strapped in their chairs.
Joan Crawford gets top billing in "I Saw What You Did" even though she is barely in it. It is actually just a cameo by Crawford, but since she as such a huge star, she gets top billing. The kids in the film did a good job, but they never really went on to do anything else with their careers. John Ireland was very convincing as a crazy murderer. He did a great job.
Even though the film is extremely corny, it is still very fun to watch. William Castle doesn't direct the best films, but he sure knows how to entertain an audience.
B- I recommend it.