More somber than the mystery puzzles and parodies in previous Boruvka books (The Mournful Demeanor of Lieutenant Boruvka, Sins for Father Knox), these five longish stories are set in the mid-1960's Prague of internal upheaval and Soviet suppression. In all of them, with varying degrees of explicitness, middle-aged cop Boruvka finds himself thwarted or weighed down by the powers-that-be. In ""Miss Peskova Regrets,"" Boruvka connects a dancer's ""suicide"" to a Party bigwig's drag-and-sex parties--but is blackmailed into silence (because of his own extramarital impropriety). The least political story, ""Strange Archaeology,"" features that always-intriguing premise: the discovery of a skeleton that leads to the solution of a bygone murder. The Soviet presence comes into the foreground in ""Ornament in the Grass""--with the (officially) unsolved killing of two teen-age girls who like it) flirt, tease, and frustrate randy soldiers. ""Humbug,"" about the murder of a candy-company employee, brings together factory politics, anti-Semitism, and institutionalized corruption. And ""Pirates"" is double-layered in issues: the killing of an old man (a probable secret-police agent) seems at first to be the work of his neighbor, a well-known dissident: but Boruvka eventually realizes that the case involves the derring-do of an American pilot who illicitly airlifts Czechs to the West. Boruvka is glummer than ever here, especially since his daughter (already an unwed mum) is involved in a politically ill-starred romance with an American. But Skvorecky shrewdly balances the angst with dry humor, fetching character-details, and crisp narration--making this a darkly entertaining, if somewhat stark, addition to an unusual series.