And they're swimming with a bunch of sharks who are definitely of the bloodthirsty sort in Robert B. Parker's Back Story (Random House Audio- Books, $29.95, 6 hours unabridged, CD, ISBN 0739302590), read as only Joe Mantegna can. Spenser reveling in his trademark droll, dry dialogue and with his serenely scary, glacially cool cohort, Hawk, and the beautiful, brainy Susan, and falling into occasional philosophic reverie has also taken on a cold case. A young woman was murdered 28 years ago during a bank hold up and now her daughter wants justice. Digging into the past turns out to be a blast or many blasts aimed directly at Spenser. Seems he's uncovered some info that some very nasty folks wanted to keep covered, and they'll go to some very nasty lengths to do just that. An ordinary Spenser caper is better than most and a good one, as this is, is always prime crime.