In his sixth outing, a retired detective tries to determine the identity of a clever killer who’s seeking revenge against him. In Florence, retired policeman Piero Trotti assists Wilma Barclay, a young American who seems lost, and takes her under his wing. In Siena, he meets Gen. Spadano, a former colleague himself contemplating retirement, who coolly informs Trotti that a professional killer is after him. The philosophical Trotti contemplates his own mortality for a remarkably long time before deciding to protect himself. Long-winded Spadano turns the revelation of the would-be killer into a shaggy dog story, complete with coffee breaks, Mafia references, and a brace of likely suspects, including postwar revolutionaries, corrupt politicians, and crime lords. Chief among these is Lia Guerro, the lover of crusading journalist Signor Gracchi, whose death she likely blames on Trotti (wrongly, in his opinion). With Wilma and his mental catalog of past enemies in tow, Trotti continues his rail journey. He tracks down and talks to a handful of former antagonists in his efforts to get to the truth and avert personal tragedy. Readers who suspect that Wilma’s continuing connection with Trotti is not accidental can congratulate themselves on their astuteness. There’s some confusion in the piecemeal mosaic of complex episodes and speculations from Trotti’s past, but it’s hard to resist Williams (Big Italy, 2015, etc.) as he unfolds his tale in tiny, deliciously wry narrative nuggets—100 titled chapters of puckish literary pointillism.