A San Francisco poet named Charlie, who has had a history of relationships with issues of commitment, meets Harriet, a charming butcher with a mysterious past. Despite his initial reluctance to engage in another relationship due to his fears of commitment and his habit of finding faults in his partners, Charlie finds himself enamored with Harriet's quirky and endearing qualities. As their romance swiftly progresses, Charlie's paranoia and the influence of his overbearing mother lead him to suspect that Harriet might not be as she appears.

As Charlie's suspicion grows, he uncovers a series of articles about a woman who marries men and then murders them on their honeymoon. This revelation rattles Charlie, causing him to obsess over the possibility that Harriet could be this notorious "Honeymoon Killer." His anxiety is fueled further by his friend, a conspiracy theory-inclined cop who indulges Charlie's fears instead of allaying them. Torn between his affection for Harriet and his escalating fears, Charlie is pushed to investigate the truth behind Harriet’s past, leading him to question whether his suspicions are the result of his own commitment phobia or if there is genuine danger in his newfound love.