Dave Garver, portrayed by Clint Eastwood, is a magnetic KRML radio disc jockey who charms listeners from his studio in Carmel-by-the-Sea, California. Each night, he artfully blends poetry with music, captivating his audience. After unwinding at a favored local bar, where he shares a delightful ritual involving corks and bottle caps with the bartender, Dave inadvertently attracts the attention of the mysterious Evelyn Draper, brought to life by Jessica Walter. During a drive home, Evelyn reveals that her presence in the bar was intentional; she had been seeking him out after hearing his name on the airwaves. This fateful meeting sparks a night of passion between them.
However, as their relationship develops, the dynamics between Dave and Evelyn increasingly take a darker turn. Evelyn begins to exhibit alarming signs of obsession and volatility, making Dave feel increasingly uneasy. She shows up uninvited at his home, stalks him at work, and bombards him with constant phone calls. The situation escalates dramatically when a jealous Evelyn disrupts a business meeting, mistaking one of Dave's colleagues for a romantic interest, which jeopardizes a crucial career opportunity for him.
In a desperate attempt to break free from Evelyn's clutches, Dave finds himself in a horrifying situation when, after yet another rebuff, she attempts suicide in his home by cutting her wrists. After rejecting her once more, this time in response to her blackmail efforts over her injuries, the vengeful Evelyn resorts to vandalism. She breaks into his house and attacks Birdie, the housekeeper, leaving her injured but alive.
As Evelyn is confined in a psychiatric hospital, Dave seeks solace in a rekindled romance with his ex-girlfriend Tobie Williams. But when Evelyn reaches out to the radio station, requesting “Misty,” revealing her recent parole, Dave’s anxiety heightens. Eerily quoting Edgar Allan Poe's haunting poem “Annabel Lee,” she hints at a newfound introspection. That very night, she sneaks into Dave's home, wielding a knife with the intention to kill him; however, he narrowly escapes her attack.
Apprehensive about Evelyn's potential wrath, Dave urges Tobie to steer clear of Evelyn. He contacts detective McCallum to have his phone tapped, anticipating Evelyn’s next move. Meanwhile, unbeknownst to Dave, Evelyn cunningly inserts herself into Tobie's life, adopting the guise of her new roommate "Annabel." Tobie eventually recognizes the reality behind this façade upon seeing the fresh scars on Evelyn's wrists but sadly finds herself unable to escape before being captured.
Amidst this turmoil, Dave connects Tobie’s new roommate to the ominous poem and attempts to warn her through a frantic phone call. Unfortunately, Evelyn intercepts the call, revealing that she and Tobie are waiting for him. Taking decisive action, Dave switches his live show to pre-recorded music and hurries home, only to discover Tobie bound and gagged.
The showdown intensifies when Evelyn confronts Dave with a knife, slashing at him repeatedly. However, Dave retaliates fiercely, delivering a blow that sends Evelyn crashing through a window, sending her plummeting onto the rocky shore below, ultimately leading to her demise. As the chaos comes to an end, Dave and Tobie escape the house, perfectly synchronized with the soothing melody of “Misty” as Dave's radio show gracefully reaches its conclusion.
