In New York City, five-year-old Mary Bennington is raised in a lavish brownstone apartment by four parents, her mother, actress Sylvia Bennington, and three adult male roommates, architect Peter Mitchell, artist Michael Kellam, and actor Jack Holden. Although Jack is Mary’s biological father, the three men have been raising Mary ever since a distraught Sylvia left her on their doorstep as an infant. When Sylvia came back for Mary, the men were too attached to let her go and came up with their unconventional living situation. The three men pitch in with every aspect of raising Mary and all attend a parents’ interview at a prestigious pre-school, the Morgan School. Although Sylvia was a struggling actress when she had Mary, she is now starring on Broadway in a production of Saint Joan. Sylvia is also dating the play’s director, Englishman Edward Hargreave. When Edward is invited to direct A Midsummer Night’s Dream at the National Theatre in London, England, he asks Sylvia to star in the production. He also proposes to Sylvia, but she delays giving him an answer. Later, Sylvia admits to her mother, Vera Bennington, that although she loves Edward, something is keeping her from saying yes to his proposal. Vera suggests that Sylvia has feelings for her roommate Peter, but Sylvia scoffs at the idea, saying that Peter will not open up to anyone except Mary. When Sylvia tells her living companions that Mary needs a more “normal” living environment, and adds that she would like to get married and have more children someday, the men are surprised. Shortly after, she accepts Edward’s proposal and tells her roommates that she and Mary are moving to England. The men are distressed to lose Mary. One evening, Edward comes to dinner at the brownstone and makes a considerable effort to get along with the three “fathers,” but they do not like him, and warn him that raising a child is not as easy. After Edward leaves, Peter and Sylvia get into an argument and she slaps him. When Mary and Sylvia leave for London, the men console themselves by throwing an ill-fated party to celebrate their “return to bachelorhood.” Before long, Peter and Michael make a surprise trip to England to see Mary, and arrive at Edward Hargreave’s family estate during a garden party. Sylvia invites them to stay, but Edward is jealous of Peter, and suggests to his friend, Elsbeth Lomax, the headmistress of Pileforth Academy for Young Ladies, that Peter likes her. Elsbeth flirts with Peter at the party, but he is oblivious as he tries to sort out his feelings for Sylvia. Sometime later, Edward chastises Mary for disturbing his papers and impatiently sends her to her room. When Peter and Michael learn from Mary that Elsbeth Lomax measured her for a school uniform, they are upset at the thought of the young child being sent away to boarding school. They secretly visit Pileforth Academy, and are unimpressed. When they tell Sylvia that her future husband plans to send Mary to the boarding school, Edward denies it. Peter pleads with Sylvia not to marry Edward, but she dismisses him. Although angry at their interference, Sylvia allows the men to stay until the wedding, but orders them to mind their own business. As Jack arrives for the wedding, he credits Peter for holding their unconventional family together over the past five years. Jack suggests that Peter never allowed himself to admit his feelings for Sylvia, and believes she is only marrying Edward because she never received a proposal from her true love, Peter. Peter confides in Jack that he loves Sylvia, but fears a bad relationship, following a disastrous, short-lived marriage decades before. In time, Peter breaks into an office at Pileforth Academy and finds proof that Edward paid Mary’s tuition for the next semester. Elsbeth Lomax catches him and tries to seduce him. Peter flees, but when his car breaks down, he telephones Michael and Jack, and implores them to somehow delay the wedding. Elsbeth offers him a ride, and Peter explains the situation. When Elsbeth gets into a car accident en route to the wedding, they borrow a motorcycle and drive across a field to make it to the church on time. Meanwhile, Michael picks up the vicar who is to perform the ceremony, but deliberately takes him to the wrong church. At the correct church, Jack disguises himself as a bumbling, aging vicar, and tries to stall the nuptials. As the ceremony begins, Mary acts as both the flower girl and the ring bearer. Jack fumbles along, trying to delay the vows, but finally is forced to pronounce Edward and Sylvia married. Peter arrives as the newly married couple walks down the aisle, and presents proof that Edward has enrolled Mary at Pileforth Academy. Edward argues that it is the best place for the young girl to stay while they are touring the play. When Mary starts misbehaving, Edward yells at her, and Sylvia is convinced she married the wrong man. After punching Edward, Peter declares his love to Sylvia, and asks her to marry him. She says she loves Peter too, and they kiss. Edward reminds Sylvia that they are now married, but Jack takes off his disguise, revealing that the ceremony was a ruse. When Michael arrives with the real vicar, he marries Peter and Sylvia.