In 1969, firefighter Frank Sullivan dies during a warehouse fire, leaving behind his wife and young son, John. Thirty years later, John, now a detective in New York City, discovers his father's old ham radio. During a mysterious aurora borealis event, John manages to contact Frank through the radio, transmitting across time as if they were conversing in real-time. The father and son bond over their extraordinary connection, with Frank aiding John in solving his daily issues.

Their communication results in unintended changes to the past, leading to a chain of events that alters their present realities. As they strive to navigate and correct these changes, they stumble upon clues involving a serial killer whose actions have far-reaching consequences for them and their loved ones. Their remarkable link continues to face challenges as they attempt to outwit the threats posed by both changes in the timeline and the relentless forces seeking to sever their extraordinary father-son connection.