As Picnic opens, Millie is sneaking a cigarette outside, while Hal and Mrs. Potts have just finished breakfast next door. It is the last day before school starts and everyone is getting ready for a Labor Day picnic to be held that evening. The main characters are introduced, and the tomboyish Millie, while pretending not to care, is shown to be envious of her older sister Madge's beauty but contemptuous of her intellect.
Madge enters. Hal, a drifter recently arrived in town and employed doing odd jobs for Mrs. Potts, is immediately attracted to her, and Madge is clearly attracted to him. When Flo enters, her wariness indicates that she perceives Hal as a threat to her plans, mainly marrying Madge off to the wealthy Alan. Flo warns Madge that a pretty girl does not have much time before her beauty begins to fade, urging her daughter to seize the moment and secure Alan's interest. Madge enjoys Alan's company but is not in love with him. Instead, she is fixated on the train whistle in the distance, which, to her, symbolizes the prospect of freedom from the small town.
The Owens' roomer, Rosemary, enters the scene and attempts to convince the other women that she is not interested in men or in marrying. But her tone indicates that marriage is the one thing she does desire. She leaves with two other single teachers. Alan arrives and embraces Hal as an old friend from college. The two reminisce, and Hal relates his most recent activities. Alan's acceptance of Hal eases Flo's worries about the drifter and validates Mrs. Potts's fondness for her new handyman. Hal is asked to escort Millie to the picnic that evening, and the act ends with Hal, Alan, and Millie leaving to spend the day swimming.
It is late afternoon, and Madge has spent the day helping her mother prepare the food for the picnic that evening. Rosemary is getting ready for her date with Howard, who soon arrives. Hal and Alan have also arrived in two separate cars. After Alan goes inside the house to help Flo, Millie sits down to draw Hal's picture. Howard leaves to get something from his car, returning with a bottle...
(The entire section is 887 words.)