Le Divorce, by Diane Johnson (Vintage, £6.99 in UK)

An American in Paris has always been a phenomenon worth noting, and Diane Johnson's novel begins promisingly with the arrival of Isabel Walker in the French capital to stay with her married, and pregnant, sister Roxy. Isabel is the epitome of California chic and she's none too impressed by the French - man, all that cholesterol and tobacco and gilded Louis-the-something fur niture! The pleasantly tart comedy of the opening chapters, however, grows flabby and slack as Roxy's interminable pregnancy drags on; and not even the piquancy provided by a selection of spicy plot ingredients, from Roxy's desertion by her French husband to Isabel's passionate affair with her brother-in-law's 70-year-old uncle, to antiques theft and finally murder, can prevent the onset of catastrophic ennui.