Plot
Mild-mannered radio executive Brad Whitaker tries hard to be a good stepfather to his wife Sara's children, Megan and Dylan, and is seemingly sterile after an accident to his testicles a couple of years ago. The kids are finally getting closer to him: Dylan confides in him about some older bullies at school and Megan asks him to take her to the school's father/daughter dance.
One night, however, Dusty Mayron, Sara's ex-husband and the kids' biological father, calls to announce he will be visiting the next day. Sara hesitates to let him into their home, but Brad convinces her it is important for the kids to see him and Dusty establish a respectful relationship.
When Dusty arrives, he immediately intimidates Brad with his tough and muscular appearance and his charm with Megan and Dylan. He talks Brad into letting him stay, despite Sara warning about his true nature. Brad soon wises up when it becomes clear he intends to reclaim his family by driving Brad away.
Dusty shows Brad up by getting the kids a dog, which Dusty names Tumor, and finishing a treehouse Brad and Dylan had been building. He also makes Brad seem racist after unwillingly firing handyman Griff after a fiasco with Dusty's motorcycle, and Dusty later invites Griff to move in with them. He tries to drive a wedge between Brad and Sara by taking them to a fertility doctor, hoping that Brad's inability to impregnate her will send her back into Dusty's arms.
Still, the two men appear to reach an understanding after jointly teaching Dylan how to defend himself from his bullies. Additionally, the couple is overjoyed to learn that Brad's sperm count has recovered, giving them hope of having a child together.
However, Brad is stunned when Dusty reveals he still intends to drive him out of the family. Desperate, Brad spends tens of thousands of dollars on gifts, including a pony for Megan, and $18,000 tickets to an NBA game for Dylan.
At the game, Dusty once again shows Brad up by revealing himself to be friends with the strength and conditioning coach of Dylan's favorite team, the Los Angeles Lakers. Brad is even more enraged when he learns that Megan has chosen Dusty to take her to the father/daughter dance instead of him.
During half-time, Brad is chosen to try to shoot a basketball from half-court to win a trip to Disney World. Drunk, he goes on a rant about Dusty before hitting a cheerleader and a disabled child in the face with a basketball. Disgraced, Brad moves out of the house. However, when Dusty tries to comfort Sara, she rejects him, and forces him to step up as a father to help his children with their busy schedules.
Four days later, Brad is living in his office at work, depressed. Dusty, meanwhile, is overwhelmed by the responsibilities of being a full-time father. When Dusty decides to leave on the day of Megan's dance, Griff convinces Brad to fight for his family.
Finding Dusty at a bar at the airport, he tries to get him to come back. Dusty admits that he cannot handle the hard parts about being a father and admires Brad for putting up with everything. Brad says that all of the terrible parts are worth it, because in the end, he is doing it for his kids. This convinces Dusty to go to the dance, and they arrive together.
At the dance, they discover the students who were bullying Dylan at school are girls. They almost fight the father of one of them when Dylan physically retaliates, as Brad and Dusty taught him to do, having assumed the bullies were boys. However, Dusty finally decides to follow Brad's lead on being a father, quelling the fight with a dance-off, while Dylan does the same thing with his bully. Brad and Sara reconcile, and Dusty decides to stay and "co-dad" for his kids.
One year later, the whole family is happy; Brad and Sara have a new baby boy named after Griff, and Megan and Dylan have finally accepted Brad as a father figure. Dusty has become wealthy, and is now friends with Brad. Dusty remarries to Karen, who has a daughter Adrianna, thus making Dusty a step-father himself. In an ironic twist of fate, he is now in exactly the same position that he put Brad in a year ago – visibly intimidated by Adrianna's more muscular father, Roger.
