When the Allies succeed in breaking the Enigma code with the Ultra machine, they need to trick the Nazis into thinking that Enigma hasn't yet been broken. So several agents--who don't know that they're on phony missions--are dispatched in 1943 to try (ostentatiously) to steal the Enigma secret from various Nazi codecenters. Among them: Italian-speaking Roberto Revere, sent to Rome--where he hides out with sexy double-agent Anna, who'll help him (for her own financial gain) to blackmail a homosexual Nazi officer into turning over Enigma photos. Meanwhile, however, the Nazis are onto Roberto's scheme: Canaris therefore announces a plan to let the code be stolen and then feed the Allies false data. (A Canaris rival, however, believes that the Hitler-hating Admiral wants to really sell out to the Allies.) So an interesting irony shapes up here--though Murphy hasn't the thriller technique to exploit it properly: the Nazis want Roberto to escape while the Allies want him, their own man, to be caught. And stuck in the middle is the top US spy in Rome, the Vatican's Father Sullivan, alias F.C. (Father Christmas)--who agonizes when his ruthless superiors order him, for dubious reasons, to set Roberto up for Nazi capture. The focus creakily revolves, then, from Roberto to the Abwehr to the Gestapo to F.C. to Washington--and also to Pope Pins XII, who defends his decision to remain silent while the Germans extend the Holocaust to Rome. Unfortunately, however, this important (if familiar) material is only tenuously linked to the rest of the plot. And neither Roberto (who winds up hiding with Jews in a monastery) nor F.C. (who dies by Nazi torture) receives enough central attention to become a strongly involving protagonist. Rather sluggish, derivative suspense, then, with each of the many plot-pieces talkily belabored--but it's sturdy and earnest, and it may pick up some clergy-oriented readers who enjoyed Murphy's flawed but noteworthy debut, The Vicar of Christ.