Peter Mitchell, Michael Kellam, and Jack Holden are living happily together with Mary Bennington, who is now five, and her mother, Sylvia. They relocate from their apartment loft to a bigger house in the city. Peter and Michael continue as an architect and cartoonist, while Jack has little acting work. Sylvia has become a famous actress and is dating director Edward Hargreave who wishes to marry her, but Sylvia is unsure how it will affect Mary. Sylvia and Peter are clearly in love with each other, although he won't admit his true feelings. When visiting, Sylvia's mother Vera warns her that he may never be able to express or admit his feelings. Sylvia realizes she wants to get married and start a family, so Jack intervenes and, knowing they are both Mary's birth parents, asks her to marry him. Sylvia rejects him, stating that he is a good father, but would make a lousy husband. Sylvia accepts Edward's proposal, announcing she and Mary will be moving to the
UK after the wedding. Inviting Edward to the apartment, Peter tests some waters on Edward showing that he doubted Edward would be a good father for Mary. When he leaves, Sylvia confronts Peter, leading to a falling out when she calls him selfish, and he reminds her she abandoned Mary once (as described in
the first film). Sylvia slaps Peter for the comment and storms off. Sylvia and Mary leave the next day for the UK. The men, depressed, try to cheer themselves up with one of their bachelor-style parties, but are still miserable without Mary and Sylvia. Peter and Michael go to the UK to visit Mary, who is unhappy without them, while Jack is filming on location in
Brazil. Peter and Michael arrive in time for the rehearsal dinner, happily reuniting with Mary and Sylvia. Miss Elspeth Lomax, headmistress of Pileforth Academy for Girls, is introduced to Peter by Edward (who tells her Peter is secretly interested in her). Peter and Sylvia apologize to each other for the fight. With the wedding imminent, Peter is concerned as Mary says Edward dislikes her. Peter and Michael realize Edward plans to send Mary to Pileforth. Edward denies it and Sylvia refuses to believe Peter, who has always disliked Edward. Jack arrives mid-argument and Sylvia and Edward leave. Peter admits he loves Sylvia but stayed silent due to Jack and Sylvia's past. Jack insists that Sylvia only loves Peter and he must follow his heart. The night before the wedding, Peter breaks into Pileforth to get proof of Edward's scheme. Elspeth believes Peter is admitting his "feelings", throwing herself at him. Very surprised and deflecting her advances, he gets away with the evidence in hand. After his car breaks down in the countryside, he calls Jack and Michael and confirms that he has the proof, but he will be late. Michael, Jack, and Mary try to stall the wedding. Michael kidnaps
Vicar Hewitt and Jack disguises himself as an elderly replacement. Peter, with help from Elspeth, heads to the wedding. During the ride, she says Edward told her Peter was interested in her, but Peter says Edward lied, apologizing for his deceit. They crashed the car into a creek bed and wind up borrowing a motorcycle from a sheepherder. After numerous delays, Peter and Elspeth arrive at the chapel. Peter shows Sylvia the truth, but she remains in disbelief until Elspeth confirms that Edward has been lying to her. Sylvia comes to her senses and confronts Edward, who tries to defend his decision. When Mary called him out for his lies, Edward shows his true colors by swearing at Mary, causing Peter to knock him out. Sylvia insists she's going home, but Peter stops her, ultimately declaring his love. Then, Edward regains consciousness, stating it is too late as they are already married. Jack then reveals himself – he has both finally proven his acting skills and rendered the marriage invalid. Peter and Sylvia wed with Mary as their bridesmaid. Mary throws the bouquet into the air as they leave the chapel, and it is caught by Jack who expressed shock. ==Cast==