Mild-mannered radio executive Brad Whitaker struggles to be a good stepfather to his wife Sara's two children, Megan and Dylan, and is seemingly sterile after an accident to his testicles some years ago. The children begin to grow closer to Brad, with Dylan confiding in him that he is being picked on at school and Megan asking him to take her to a father/daughter dance at her school. One night, Dusty Mayron, Sara's ex-husband and the kids' biological father, calls and discovers Sara's marriage with Brad. He suddenly announces he will be visiting the next day. Sara hesitates to let her ex-husband into their home, but Brad convinces her that it is important for the kids that their father and stepfather establish a respectful relationship. When Dusty arrives, Brad is immediately intimidated by his tough and muscular appearance and his charm with Megan and Dylan. Dusty repeatedly talks Brad into letting him stay, despite Sara warning about Dusty's true nature. Brad soon wises up when it becomes clear that Dusty intends to drive Brad out of his kids' lives and reconcile with Sara. After Dusty shows Brad up again and again - getting the kids a dog, finishing a treehouse that Brad wanted to build with Dylan, making Brad appear to be racist - Dusty tries to drive a wedge between Brad and Sara by taking them to a fertility doctor, hoping that Brad's inability to impregnate Sara will send her back into Dusty's arms. Still, the two men appear to reach an understanding after working together to teach Dylan how to defend himself. Additionally, Brad and Sara are overjoyed to learn that Brad's sperm count has increased significantly (implied to be a result of Dusty "invading his territory"), giving them hope of having a child together. However, Brad is stunned when Dusty reveals that he still intends to drive Brad out of the family. Desperate, Brad spends tens of thousands of dollars on early Christmas gifts, including a pony and $18,000 tickets to an NBA game. At the game, Dusty once again shows Brad up by revealing himself to be friends with the coach of Dylan's favorite team, the Lakers, and an enraged Brad begins drinking heavily. During half-time, Brad is chosen to try to shoot a basketball to win a prize. Drunk, Brad goes on a rant about Dusty before accidentally pelting a Pelicans cheerleader and a disabled child in a wheelchair in the face with basketballs. Humiliated, Brad moves out of the house; however, when Dusty tries to comfort Sara, she rejects him, and forces him to step up as a dad to help his kids with their busy schedules.