Marian McPartland has a great story. Born in England, raised in a good middle-class home, she scandalized her parents by joining a four-keyboard vaudeville act--Billy Mayerl & His Claviers--during World War II. She adopted jazz when she married cornetist Jimmy McPartland, famed ringleader of Chicago's trad-jazz scool (she fell for him when he pulled some strings to surprise her with a top-notch piano in the middle of war-torn Europe). She followed him back to the States, played the trad-jazz circuit, then took a two-week trio gig at the Hickory House that ended up lasting ten years, establishing her on the New York scene. After 1970, instead of resting on her laurels, McPartland turned out a series of records (first for her own Halcyon label, then for Concord) on which her style continued to evolve and her repertoire grew to include songs by younger, progressive artists. Since 1978 she's hosted Piano Jazz, the longest-running jazz program in NPR's history. The show provides an outlet for her musical intellect and conversational grace, which distinguish the program as much as its guests. But not even Piano Jazz fully reveals her puckish humor; for that you need to see her in performance. At her 85th birthday celebration in New York last March, she shared the stage with a couple dozen former radio guests--including Tony Bennett, Jon Faddis, Norah Jones, Chris Potter, and pianist turned impresario George Wein--and outshone most of them with her quick-witted repartee, both verbal and musical. She plays the piano with an elegant, still-energetic touch and an authoritative swing that's almost indecent for such a grand dame. Here McPartland will play with her longtime Chicago accompanists, bassist Jim Cox and drummer Charlie Braugham. Thursday, September 25, 8 and 10 PM, Friday and Saturday, September 26 and 27, 9 and 11 PM, and Sunday, September 28, 4 and 8 PM, Jazz Showcase, 59 W. Grand; 312-670-2473.