Harry, a trombone player, meets and falls for Julie at the La Brea Tar Pits Museum in Los Angeles. The two have an instant connection and make plans for a date. Later that evening, Harry accidentally oversleeps and misses their meeting time. Frantic to connect with her, he rushes to the diner where Julie works, only to find she has left. While using a payphone outside the diner, he inadvertently picks up a misdialed call meant for someone else: on the other side of the line is a panicked voice from someone inside a missile silo, who reveals that a nuclear war is imminent, and missiles will strike in less than an hour.

As the gravity of the situation sets in, Harry returns to the diner to inform its patrons. Skepticism quickly turns into fear as some start believing his story. A chaotic chain reaction ensues, with Harry desperately trying to find Julie amidst growing panic and confusion in the city. Meanwhile, various characters from the diner devise plans to evacuate, leading to a mad rush through an increasingly frenzied Los Angeles. Harry's love for Julie drives him to heroic lengths as he navigates through the nightmarish chaos to reunite with her before time runs out. As events rapidly escalate, the reality of the looming catastrophe becomes undeniable—a race against time in a city about to unravel.