A young couple, Polly and Ray Cutler, travel to Niagara Falls for a delayed honeymoon and find themselves next door to George and Rose Loomis. Their neighbors' relationship appears to be strained, with the glamorous Rose openly flirting while George, a troubled Korean War veteran, grows increasingly suspicious and irate. Polly becomes entangled in their tumultuous affairs when she witnesses Rose conspiring with her lover, Patrick, to murder George.

As tensions escalate, unanticipated twists unfold that heighten the peril for everyone involved. Polly's initial concern turns to fear as the situation becomes more dangerous and volatile. The dramatic scenery of Niagara Falls provides a stunning backdrop for the unfolding thriller, creating an atmosphere of impending doom contrasted with idyllic moments of young love. The plot drives forward with increasing urgency towards a climax that puts loyalty and survival to the test.