Charlie (John Travolta) and Dan (Robin Williams) are best friends and co-workers. Seven years prior to the present time of the movie, Dan was once married and when he divorced he was very depressed. In order to cheer Dan up, Charlie takes him on a wild vacation where Dan meets a woman named Vicki (Kelly Preston) who he thinks is his soul mate. Along with Vicki is her equally beautiful but weird best friend Jenna (Rita Wilson) who is overly obsessed with her hands because she is a hand model. Dan and Vicki marry the same night they meet but their love affair is short lived. Seven years later, Vicki arrives back in town and announces to Dan that they have twins: Zach (Connor Rayburn) and Emily (Ella Bleu Travolta) together.



Dan offers to take care of the children the same day he meets them after Vicki has to go to jail for two weeks due to an activist crime. Because Dan's condo does not allow children, he has to board with Charlie. Whilst this is happening, Charlie and Dan are about to score their greatest gig in the history of their careers with a Japanese corporation. At first, Charlie doesn't want Dan hanging around the children, but later warms up to the idea. Dan does not know how to interract with his kids, and at night he resignedly groans to Charlie, "I just shook my daughter's hand goodnight". At camp, the four turn a three day trip into a nine hour one after unwittingly convincing the instructor that Dan and Charlie are homosexual partners, and destroying a statue of the founder of the camp.



The morning they arrive back home, the kids spill Dan and Charlie's pills and clumsily put them back in the wrong bottles, believing they remember where they belong.. This causes side effects for the both of them, with Dan not being able to speak and having odd sight perception during a golfing game with Ralph and the possible Japanese co-workers, and Charlie's face freezing in a smile along with a neverending appetite while he is trying to woo the attractive American-Japanese translator Amanda (Lori Loughlin) at her grandmother's funeral, which results in him grinning as Amanda is grieving and crying along with eating grandmother's last famous rhubarb pie which she made within the last hours of her life.