During the final months of World War II, a young man named Marion is traveling by hitchhiking to the small town of Plainfield. After several unsuccessful attempts to catch a ride, he finally steps in front of a car driven by a young woman. She tries to go around him but ends up crashing and blowing out a tire. Marion quickly offers to fix the tire, and in return, the woman, initially hostile, agrees to give him a ride. She is upset with him for causing her accident and also angry that he seems to have avoided military service—an assumption based on his appearance. When she notices a uniform with many decorations in his suitcase after he goes to buy gas, her attitude softens, revealing more curiosity and friendliness.
The woman introduces herself as "Willie" and shares her real name, Wilhelmina "Willie" Hammond, a member of a wealthy and prominent family. Marion, on the other hand, is convinced that she is a spoiled rich girl running from an arranged marriage with Alvin Bailey, a socially prominent young man. Their interaction is filled with a mix of suspicion, mystery, and budding friendship, as they exchange their names but keep many details about themselves secret.
Soon, their journey takes a turn when police officers stop them over allegations that Willie has stolen Bailey's car. Both are taken into custody but are released after Bailey confirms their innocence over the phone. Willie then takes Marion to her family mansion, pretending she is the family's secretary because she's lost her key. This leads to another misunderstanding when Marion has to crawl through a window to enter, causing them to be detained again. Despite this, their identities are eventually confirmed, and their story hits the headlines, resulting in their release once more.
Initially, Willie suspects that Marion might be a deserter from the Army, but upon learning he was honorably discharged for medical reasons, she offers him a job as the family's chauffeur. The estate's eccentric caretaker, Wiggins, however, is wary of Marion's presence. Meanwhile, Willie's widowed mother, Mrs. Hammond, her "old maid" Aunt Harriet, and her younger sister Patricia return from New York City. Also arriving are Alvin Bailey, who disapproves of Willie's association with Marion, and his physically strong friend and sidekick, Champ. Mrs. Hammond and Bailey both see Marion as a potential gold digger and try to buy him off, while Bailey even sends Champ to alert the police.
Despite these challenges and family disputes, Marion proves his true character and reveals himself to be a nationally recognized war hero. He was hitchhiking not out of necessity but because he prefers to avoid publicity. His heroism and integrity win over the town's mayor, the governor, and the residents of Plainfield, who honor him with a parade. Marion explains that he was inspired by a vivid description of his hometown by a friend he lost in battle and decided to settle there because he has no other strong ties to any place. As Marion prepares to leave, Willie, now in her wedding dress, chases after him, and in a heartwarming role reversal, he offers her a ride, symbolizing their newfound understanding and connection.
