On graduation day at the Hattie Greenfield Agricultural College, crabby Hattie, who donated the land and buildings for the college twenty-one years previously, is angered by the students' good-natured attempt to poke fun at her. Hattie refuses to donate more money to the school, despite the pleas of the college's president, Professor Edgar Boggs. Determined to raise enough money for needed buildings, Edgar and the school's veterinarian, Dr. Hall, organize the students and turn the school into a summer vacation lodge called the "Hi, Neighbor Lodge." A better-equipped lodge across the lake threatens to monopolize the tourists until the kids hit upon a scheme involving a pen-pal Lonely Hearts club. The students write to the club's members, inviting them to come to the lodge to meet other single people. Soon business is booming, and only one more month's bookings are needed to raise all of the required funds. A newspaper story about the lodge and the club raises the ire of Hattie, who deems the proceedings inappropriate. She descends upon the lodge with her niece Dorothy, sister Vera and lawyer, Don Wilson, who is engaged to Dorothy. Hattie insists on reclaiming the school property and orders everyone to leave. Determined to thwart Hattie, some of the boys decide to trick her into staying. They arrange for Don to come into contact with some poison ivy that night, and the next morning, Dr. Hall diagnoses his rash as measles. A quarantine is ordered for one month, and Don is bundled off to bed. While Vera pursues Roy, one of the students, Dr. Hall and Dorothy spend time together and fall in love. Even Hattie discovers a touch of romance at the lodge when Edgar, who was her childhood sweetheart, tries to recapture the days of their youth. Everyone's good humor is destroyed, however, when Don sneaks out to a local hospital and learns that he does not have measles. He exposes Dr. Hall's deception, and an angry Hattie declares that the school will be shut. Dorothy tells Hattie that she is staying to marry Dr. Hall, but when he learns of Hattie's plans, Dr. Hall makes a deal with her that he will give up Dorothy if she will keep the school open for Edgar's sake. Dr. Hall breaks off his relationship with Dorothy, who then returns with her relatives to the city. Brokenhearted over Dr. Hall, Dorothy resumes her engagement to Don, but on the day of the wedding, Vera returns to the school and informs everyone of Dr. Hall and Hattie's pact. Edgar and the kids rush to Hattie's mansion and establish a picket line to protest her unfairness. Don and Dorothy call off their wedding, and Hattie finally accepts Edgar's comforting. The Greenfields then travel to the school, where Dorothy and Dr. Hall are reunited.