Rappers with Mos Def's reputation and charisma aren't supposed to wait five years between albums, but the Brooklyn native has been legitimately distracted. He can act -- and Hollywood adores him for it.

The Internet Movie Database lists about a dozen screen credits for him since 1999, the year he released his first solo disc, "Black on Both Sides," to critical acclaim. One acting job got him an Emmy nomination (as pioneering heart surgeon Vivien Thomas in the movie "Something the Lord Made"), and he made his Broadway debut in 2002, appearing in the Pulitzer Prize-winning, two-person play "Top Dog/Underdog." There is plenty of work to come, too: He'll play Ford Prefect in next year's "Hitchhiker's Guide to the Galaxy."

Despite those career developments, the Mos Def who swaggers through the excellent "New Danger" is pretty much the same one who helped invigorate underground New York hip-hop in the late '90s. The only change in his game is a continuing fling with electric guitar noise -- his rock project, Black Jack Johnson, has not yet released an album, but its influence here is vital.

That's because "The New Danger" is anything but slick and stylish. Although the tracks are lovingly constructed, they have moments of messiness and spontaneity. The rock isn't a gimmick; it's smartly absorbed into the disc's worldview. And despite his growing celebrity before the cameras, Mos Def knows only one way to behave as an MC: as a cocky street philosopher with no trust in the system.

"And my work is personal, I'm a working person, I put in work, I work with purpose," he says in "Champion Requiem," pinning down the overarching ethos of the disc. The goal here isn't money or fame -- it's personal satisfaction. The grooves speak the same language, always leaning toward grittiness where a more pop-obsessed rapper might crave a cleaner hook.

The method might be most effective on the terse, booming "Ghetto Rock," one of several songs that feature the members of Black Jack Johnson, named in honor of the old-time heavyweight champ. While drummer Wil Calhoun (Living Colour), keyboardist Bernie Worrell (Parliament) and guitarist Dr. Know (Bad Brains) maintain a funky slow-burn, Mos Def wends his way through a series of party rhymes, battle calls and shout-outs, ending with the chorus "Yes, we are so ghetto, yes we are rock-and-roll." It's cool, not corny.

The more experimental tracks get similar results. "Boogie Man Song," with its jazz-club vibe and Mos Def's amateurish singing, could've been a disaster, but instead it sounds emotional and real. "Let me be your favorite nightmare, close your eyes and I'll be right there," he croons, avoiding the urge to play a traditional loverman. Likewise, the loudly soulful "Beggar," the splashy, bluesy "Blue Black Jack" and the garage-rock of "The Easy Spell" each have their place.

Give any talented, versatile MC five years to write and record a disc, and that kind of inventiveness might be inevitable. But in Mos Def's case it also sounds certifiably natural. His time in front of a camera has obviously deepened his ability to communicate, and if there's a false note on "The New Danger," it comes only when he's testing his boundaries.

Mos Def delivers in "New Danger."Despite his celebrity before the cameras, Mos Def knows only one way to behave as an MC: As a cocky street philosopher with no trust in the system.