Actually, the volume collects seven cases from the files of L.A.'s amateur PI Ezekiel ''Easy'' Rawlins, but who's counting? Arranged chronologically and linked thematically, the stories amount to more than the sum of their pieces. They're packed with significant events -- one major recurring character dies, another is resurrected, and Easy experiences severe turbulence in his romance with Air France stewardess Bonnie Shay. Mosley's prose remains delectably hard-boiled: ''Inez was the color of pure chocolate. But if chocolate looked like her I'd have weighed a ton.'' And after last year's less-than-satisfying Rawlins novel ''Bad Boy Brawly Brown,'' Six Easy Pieces marks an overdue return to solid storytelling form.