Sherborne Eppe, 24, was put in a toney loony bin in Ohio seven years ago for quite sensibly throwing his rich WASP mother's gigolo boyfriend in a swimming pool. But now ""Bomie"" is out, only to find himself in Cleveland and penniless. So he takes the first job coming--selling used-car parts (all stolen, as he belatedly discovers)--and it's the first adventure of a basically tabula rasa innocent. Exploits to follow include: accidental (everything with Bornie is accidental) involvement in a reform mayoral campaign in East Heidelberg, Ohio; a job as an investigative reporter for a Pittsburgh TV station, with a first assignment to a Pennsylvania town that's being robbed blind by a phony, raking-it-in evangelist; and, running throughout, a phone romance with a woman poet, Beth, whom Bomie started talking to one day when he was selling the stolen auto-parts. MacLeish (The Man Who Wasn't There) forces absolutely none of this and lingers when the lingering makes for good, fond satire: there's an especially sweet section when Bomie, along with Hannibal (the big, black private-eye he picked up in Cleveland), nurses a 97-year-old man into a happy death. Above all, MacLeish has a real winner in Bomie, who's just the right charming and affectationless hero for this crisp, clean, nice novel--""romance"" is truth-in-packaging here. So if there's to be a second book of Eppe, as the title suggests, that's fine with us.