The last thing you expect when the stunning young blonde Marnie Baumer strides to the stage of the FireBird Café is a musical comedy act. The juxtaposition of her innocent and wholesome-looking beauty with her sudden explosions of inspired vulgarity is as surprising as it is funny. Yes, the lady has got quite a mouth on her; it's fitting that she's appearing at the FireBird while the fleet is in, because she swears like a sailor.

Baumer's act is a carefully constructed arc in which she takes the audience on a raucous, double-edged emotional journey. We start at betrayal, descend through anger and detachment, and bottom out in despairing loneliness. Then comes the ascent--sexual reawakening and, finally, the sweet discovery of a kindred spirit. Under Erv Raible's astute direction, Baumer delivers smartly chosen material with a voice that combines little-girl breathlessness and a brassy Broadway sound.

The fun begins right at the start with Baumer's rendition of the lush, romantic "When I Fall In Love" (by Victor Young and Edward Heyman). In the course of the song, we learn that the singer's boyfriend has gotten cold feet and their wedding plans have crashed and burned. Happily, Baumer's performance does quite the opposite, really taking off as each song flows into the next. "My Sort of Ex-Boyfriend" (Carol Hall) and "The Best Thing to Happen to Me" (Babbie Green) continue Baumer's tale of woe with a knowing, comic edge. These songs, and her performance of them, are couched in the formula: tragedy + time = comedy. Thanks to Baumer's creative consultant, Julie Halston, the show is firmly anchored in realistic pain cut with distance and attitude, so that the humor works.

Baumer salts her show with a few ballads, and she has a pretty good handle on the serious stuff. Her rendition of "Southbound Train" by Julie Gold is sensitive and searching--even if not always finding. She more fully successfully delivers "Lover's Lullaby" (by Julie Flanders and her musical director, Jeffrey Klitz); the sincerity of the song is shared with the audience in a genuinely organic performance. And, speaking of Jeffrey Klitz, his arrangements deftly support Baumer without distracting.

The thing to remember is that Baumer is a young performer; this is only her second cabaret show. We saw her first, at Eighty Eight's a couple of years ago and, with the help of Raible, she's made an extraordinary leap forward. She still has a distance to go to smooth over the raw edges--some of her ad libs are less than adept--but her talent is obvious. At this point, she's at her best in big, broad comedy material like the outrageous "Baltimore Blows" (Jonathan Sheffer and Howard Ashman) and the hilarious voyeur number "Better Than T.V." (Kristina Olsen). Baumer is less successful with sly material like "It's Only a Broken Heart" (Carol Hall) and "Bored" (Jason Moscartolo and Naomi Kukoff), falling short because she tries too hard. It could be she doesn't entirely trust the material, her talent, or the audience, but she sometimes oversells rather than underplays. You catch her acting, and it kills the comedy.

All Marnie Baumer needs to do is less. When she learns how to land on a line a little more deftly and move to the next a little more quickly, she's going to be a firecracker.