A handsome drifter ignites passions at a small-town Labor Day picnic.

Early on a September morning, drifter Hal Carter rides a freight train into a small Kansas town seeking his old college friend, wealthy Alan Benson. Wandering toward town, Hal stops in front of elderly Helen Potts' house and asks if he might do any odd jobs for her, but Helen declines, explaining that it is Labor Day and everyone is preparing for the annual town picnic. Charmed by Hal's direct sincerity, Helen nevertheless allows him to clean her lawn and prepares him lunch. Hal then asks Helen about the Bensons, and she reveals that Alan is dating her neighbor, the beautiful Madge Owens, who lives with her mother Flo and younger sister Millie. Next door, meanwhile, Millie and Madge quibble about boys while spinster schoolteacher Rosemary Sydney, who boards with the Owens, dismisses the romantic prospect of the picnic. Later that morning, Hal arrives at the Bensons' affluent home to reunite with a delighted Alan, and the young men reminisce about college. At the Owens' home, Flo fits Madge with a striking new dress for the picnic, and inquires about the seriousness of Madge's relationship with Alan. While Millie laments that she is always overlooked because of Madge's good looks, Madge envies Millie her college scholarship and intellect. When Alan drives Hal to the family business, Hal confides his determination to find success and Alan agrees to give him an entry-level job at the company. Alan then invites Hal to join him and the Owenses for a swimming date and the picnic. After the swim, Alan confidently predicts that Madge will be crowned the seasonal Queen of Neewollah, "Halloween" spelled backwards. Later, at the Owens' house, Rosemary bitterly speculates that her beau, mild businessman Howard Bevans, will arrive for the picnic drunk. Flo is disappointed when Madge decides to wear a less fancy dress to the picnic, but pleased that Alan is nevertheless attentive to her daughter. While Hal drives Millie to the picnic in one of Alan's cars, Flo rides with Madge and Alan. Worried that Hal might be a bad influence, Flo questions Alan about him and learns that Hal grew up poor and won a sports scholarship to college, but nevertheless flunked out. On their way to the picnic, Rosemary initially resists Howard's offer of a sip of whiskey, but then gives in. During the festive afternoon, Hal joins Millie in several contests, and after the group eats, Alan grows annoyed with Hal's good-natured tall-tales while noticing, along with Flo, Hal and Madge's mutual attraction. As the sun sets, Howard and Rosemary continue to drink and Rosemary grows increasingly restless. The Owenses and their friends then excitedly gather on the pier to hear the announcement for the "Neewalloh" queen and are pleased when Madge is presented on as the winner. Dancing begins and a drunken Rosemary attempts to make Howard dance with her. When he refuses, Rosemary forces Millie to dance with her, and Hal playfully dances with Howard, which enrages Rosemary. Hal then dances with Millie until Madge spots them. When Madge and Hal begin a sensuous dance together, Helen watches admiringly, but Flo is alarmed. Also disturbed by the couple's intimacy, Rosemary lashes out at Hal and drunkenly breaks up their dance, embarrassing Hal by tearing his shirt when he attempts to pull away from her. When Millie declares she is feeling ill, Flo blames Hal for getting her drunk. Alan arrives and viewing the spectacle, accuses Hal of being a fake and a bum. Distraught, Hal rushes away and is followed by Madge. Howard apologizes to the group for providing the whiskey, while in the parking lot, Madge apologizes to Hal for Alan, but Hal angrily tells her that he is leaving town on the next freight train. When Madge tries to convince Hal to remain, he calls himself a bum and admits he went to reform school and lost countless unsuccessful jobs. Madge nevertheless praises Hal, admiring his confidence and carefree nature. When Hal reveals that his parents rejected him, Madge kisses him and confides her fear of being cared for only because of her looks. Hal misses the next freight train and stays with Madge. Howard, meanwhile, drives a dejected Rosemary home, and she pleads with him to marry her, explaining that her life is utterly empty. When he refuses and asks for things to remain the same between them, Rosemary declares they cannot see each other again unless he intends to marry her. Hal escorts Madge home early in the morning, concerned about her and whether he should remain in town and work for the Bensons. Later, when Hal returns the car to the Bensons, he discovers that Alan has reported the car stolen and summoned the police. When Alan demands that the police arrest Hal, Hal insists that Alan admit he leant him the car and that his anger is really jealousy over Madge. Alan strikes Hal, who knocks him and the policemen down before fleeing in Alan's car. Hal abandons the car, evades the police and rushes to Howard's for help. The next morning, when Howard comes to the Owenses to reiterate that he will not wed Rosemary, she misunderstands and enthusiastically tells everyone that they are marrying. Flo informs Madge that Alan has telephoned, while Howard secretly tells her that Hal is waiting to see her outside. Madge meets Hal in the yard where he reveals that although he must leave town, he loves her and wants her to come to Tulsa with him. Panicked, Flo intervenes and begs Madge to stay and marry Alan, but Hal pleads with Madge to do what she wants. Confused, Madge does not respond and, while rushing away to catch a passing freight train, Hal continues beseeching Madge to join him. Later, in their bedroom, Millie confronts Madge, encouraging her sister to be smart and to go with Hal. When Madge comes downstairs with her suitcase packed, Flo becomes hysterical, but Madge remains determined. Helen comforts Flo as Madge catches the Tulsa-bound bus.