Who threw a fire-bomb into Club Sophia (a new disco in the Plaza Hotel basement) during the opening-night festivities, thus burning 43 people to death? That's the puzzle for N.Y. fire marshal Terry Ahearn--who gets little cooperation from his rivals, the city cops. And Terry also has to deal with distractions on the home front: his socialist-but-bigoted father over in Brooklyn is fuming over kid sister Maureen's affair with a Brazilian guitarist; and Terry is feeling ambivalent about his affair with upper-class, clown-to-earth Melissa. Still, there are some good clues to follow: a man in a cape seen near the crime spot; the remnants of the fire-bomb bottle; and, above all, the fact that the fire-bomb contained amyl nitrate--a sex-enhancing drug in wide use among homosexuals. So Terry and his pal Jose manage to pinpoint the culprit--he's a discreetly gay, quite psychotic fashion-magazine publisher with grudges against a couple of people at that ill-fated party (one of whom survived!); but since they have no real evidence, they have to catch the psycho in the act, as he tries the same thing again at a costume ball. And along the way, the marshals also finger some city-government corruption (a slimy official who gave Club Sophia a fire-law variance that proved lethal) and stop in at some tragic South-Bronx fires. . . . With less direct firefighting data than Smith's other books (and enough homosexual stereotypes to drive gay activists up the nearest wall)--a solid, straightforward mix of sleuthing, action, domestic drama, and blue-collar urban discontent.