Frequency

John Sullivan is a New York City firefighter who is haunted by the death of his father 30 years ago in a warehouse fire. One night he finds his dad's old ham radio and begins playing around with it, precisely at the time that an atmospheric anomaly changes the frequency of the radio. John finds that somehow, he is able to communicate over the radio with his father Frank 30 years ago. He is able to warn Frank of his impending death so he avoids it, but in changing the past, other things also change. Suddenly Frank died of lung cancer, not in a fire. And suddenly, his mom was the victim of a serial killer years ago. Working together to change the past again and avoid this disastrous outcome, Frank and John communicate over the ham radio to save John's mother's life.