Two one-dimensional detection cases of the sort that seem to be proliferating. These feature the Bloodhound Gang of TV's 3-2-1 Contact. In The Case of the Cackling Ghost, Professor Bloodhound's three young employees--ages 10, 15, and 16--are summoned to a large country house, where an old woman is bothered by nightly visits from a ghost. The ghost, the trio soon discovers, is really clumps of moths attracted by pheromones--an illusion cooked up by the woman's debt-ridden nephew who hopes to frighten her into turning over her precious, but reputedly curse-ridden necklace. In . . . Princess Tomrorow, the gang is called as witnesses for a shady couple who pretend to predict horse-race results--but the corroborating letter received by the agency has actually been mailed after the race. The one they witnessed being mailed before the race has been invalidated by a wet but deliberately glueless postage stamp. They're both clever tricks, but of a sort that usually come five or ten to a volume. There's no attempt to flesh out the puzzles, and not a trace of the Fleischman wit and vigor.