Man-boys at play

If YOU PUT the collected works of Will Ferrell, Adam McKay and Judd Apatow in a pot, boiled off the excess and let the remainder cool, you'd have something very much like "Step Brothers." The story of two overgrown adolescents who become sudden kin when their single parents marry, it's "The 40-Year-Old Virgin" with two 40-year-old virgins, "Knocked Up" without the knocking up.

Produced by Apatow and directed by McKay, who co-wrote the script with Ferrell, "Step Brothers" is not a retread so much as a reduction, stripping away the magical pretext of "Elf" and the period trappings of "Anchorman" to get to the heart of the thriving man-boy genre. The movie's characters don't just act like children; for all intents and purposes, they are.

Apart from their thinning hair and doughy torsos, Dale (John C. Reilly) and Brennan (Will Ferrell) are the spitting images of early-'80s adolescence. Dressed in worn "Star Wars" tees, they cherish their samurai swords and drum kits, happily sponging off the parents who have spent the last quarter-century searching for the right way to shove them out of the nest.

When Brennan's mom (Mary Steenburgen) and Dale's dad (Richard Jenkins) shack up, their sons are forced to share a room, which leads inevitably to conflict since neither boy is used to sharing anything at all. Dale, the more obstreperous and sullen of the pair, verbally pounds on his unwanted roommate. Brennan gets back at Dale by befouling his precious drums in a manner consistent with adolescent boyhood and Apatow movies.

Territorial markings aside, Dale and Brennan soon find out they have more in common than not, including an intense dislike of Brennan's younger brother Derek (Adam Scott), an oily, insincere executive at a helicopter-charter firm with sculpted abs and a Bluetooth.

Unctuous, brutish and self-involved, Derek has the monstrousness of Ferrell's characters in "Anchorman" and "Talladega Nights" without any of their redeeming innocence. It's the movie's plum part and Scott runs mightily with it, creating a character so pure in his venality that you can't help but admire his determination even as you pray for his painful demise. For Dale and Brennan, Derek serves as a nightmare vision of adulthood, a loser's caricature of what it takes to win. If that's success, who wouldn't prefer to fail?