Among the entries chosen for publication from St. Martin's first private-eye contest, Tierney's middling debut features a surly, all-but-retired Indianapolis p.i. named Shanahan; his dog Casey; his old codger pal Harry, who's slavishly devoted to the Cubs; his romance with the 40-ish Maureen; and a client, Mrs. William B. Stone, who wants to find her husband--except that he's dead, and, what's more, he'd dropped her as his beneficiary. Accessing Stone's financial files with the help of techno-wizard teen-ager Marmony McCord, Shanhan discovers some very fishy cash transactions. He also learns that Stone was in love with another man, now dying of AlDS; and that the man's sister was Stone's maid, now floating face down in a canal. Then, working with computer-imaging and Stone's dying lover, Shanahan springs ti trap, nabs Stone's murderer, and, happily, doesn't even have to present an itemized expense account before his client pays the bill. Pretty obvious crooked-cops stuff; bland writing; so-so pacing. And Shanahan's more interesting when he's not working than when he is (dreaming about first wife Elaine, for instance, or brushing off his grown son).