Only seven of the stories here--there are 31 in all--have not appeared before in book form. From Tales of the Black Widowers, More Tales of the Black Widowers, Casebook of the Black Widowers, and Banquets of the Black Widowers come 15 specimens of the Black Widower club formula: chatty musings on a puzzle (often involving literary or historical trivia), featuring some genuinely clever twists as well as several groaners. Briefer, but usually lamer, are the similar Union Club symposia, three of which did not appear in The Union Club Mysteries: one of the new stories turns competently on a bit of linguistics; the other two are Asimov at his feeblest. The best of the remaining entries is "Nothing Might Happen," a previously uncollected 1973 story from Alfred Hitchcock's Mystery Magazine: despite a predictable final twist, there's wry appeal in the premise here--as the nephew of a wealthy writer tries to have his uncle killed, obliquely, by writing provocative, belligerent responses (in his uncle's name) to crazy-angry fan letters. The rest include two strained juveniles, the final sf/mystery outing for extra-terrologist Wendell Urth (a long-winded affair involving a "double and bilingual pun"), and a cryptogram based on atomic numbers. Even at his best, Asimov-the-mystery-writer is a minor, one-dimensional mass producer--primarily for fans of number-games, puns, and the like. And not all these stories are prime Asimov. Still: a solid, generous sampling--especially for collections that don't already include all those previous story compilations.