Commercial jingle writer Charlie Harper (series star Charlie Sheen) is a wealthy bachelor with a house at the beach, a Jaguar in the garage and an easy way with women. But his Malibu lifestyle is interrupted when his uptight chiropractor brother, Alan (series star Jon Cryer), arrives unexpectedly with Alan's 10-year-old son, Jake (series star Angus T. Jones). Alan's wife, Judith (series star Marin Hinkle), suspecting that she may be gay, wants a divorce. Charlie reluctantly allows Alan and Jake to live with him temporarily, but as it becomes increasingly obvious that Judith is never going to relent, Charlie and Alan's self-obsessed, controlling unmarried mother, Evelyn (series star Holland Taylor), offers to let father and son live with her. However, by that time, Charlie has formed a close bond with the clever Jake, even learning a few things about poker from the boy. Charlie also finds out that pretending to be a single dad with a cute kid can be a great lure for women. Meanwhile, Charlie tries to evade Rose (series star MelanieE Lynskey), an attractive, offbeat neighbor who had a brief fling with him and remains determined to stay in his life by whatever means necessary. Missing Jake, Charlie surprises even himself and asks Alan and Jake to live with him permanently. Despite their strained relationship, the brothers discover that they have one thing in common: They both love Jake and want what's best for him. Together these two-and-a-half men face the challenges of growing up.