From Harvey to Play It Again, Sam, the hallucinatory alter-ego gimmick has produced endearing comic results in plays and films. Here, however, as paperback-mystery-writer Hank Mercer solves a crime with help from his fictional detective (a hallucination), the effect is more preciously strained than sprightly. Hank is having lunch with his publisher, vowing to replace popular series-hero Biff Deegan (a Mickey Spillane type) with a more cerebral shamus. . . when a beautiful woman, leaving the restaurant with two men, sends Hank a ""Help me"" message. So Hank starts sleuthing--following the woman's trail to a posh art-dealer, a Manhattan hotel, a deserted Long Island inn, a swanky hair salon, and the Soho loft where she's being held captive. Hank even manages to rescue her (with lots of help from ""Biff""), bed her (with leering comments from ""Biff""), and hear her story: she's in peril because she knows about the smuggling of art treasure from Italy. But, as usual, that's not the whole truth--as Hank learns in a final showdown with the bad guys. . . followed by a reconciliation with his alter ego: ""There were a thousand things I wanted to say to him, but for the moment, it seemed enough just to enjoy his massive, comforting presence beside me."" Serviceable plot, with a couple of good publishing-world laughs (the Italian translator of Hank's books has a disturbing tendency to mangle English idioms)--but the Hank-and-Biff premise, alternately cutesy and pretentious, will put off most readers.