This third outing for San Francisco p.i. Jeremiah St. John (St. John's Baptism, According to St. John) begins with a solidly intriguing setup. Wealthy, svelte widow Nancy Gutman is convinced that S.F.'s psychotic, serial ``April Fool Killer'' is her son Vincent, supposedly killed in Vietnam back in `72. So St. John, with sidekicks Mickey (sexy, aloof) and the Chief (towering Seminole), goes looking for Vincent--tracking down his ex-wife and his daughter, who's a hooker at the ``Seven Veils Ranch'' in Reno. Babula's promising idea, however, soon falls apart--as corpses pile up (Vincent's, the daughter's) and a tangle of tedious subplots is dragged in: a fanatical general's secret army of MIA Vietnam vets; a TV evangelist's adulterous wife; an extortion scheme against Vietnamese merchants. And the result is another overknotted, undertextured serving of shamus nonsense--breezily harmless but finally wearisome, with St. John's smirky narration and lame running gags about his pursuit (including a tennis duel) of the luscious Mickey.