In a small Kansas town, the Labor Day festivities are about to commence when a charming drifter named Hal Carter arrives by freight train, hoping to find work. He reconnects with an old college friend, Alan Benson, whose father owns a large grain elevator. Hal's rugged good looks and confident demeanor capture the attention of the local women, especially Madge Owens, a beautiful girl who is dating Alan. The annual picnic becomes a backdrop for rising tensions as Madge finds herself drawn to Hal, causing her to question her current relationship and aspirations.

Throughout the day, the town's underlying social dynamics and personal struggles come to light. Flo Owens, Madge's mother, is eager for her daughter to secure a stable future with Alan, while younger sister Millie seeks her own identity away from Madge's shadow. Rosemary, an aging schoolteacher boarding at the Owens' house, faces her own dilemmas regarding love and loneliness. These intersecting lives and simmering emotions reach a climax at the picnic, setting the stage for critical decisions and revelations that could alter their paths forever.