Head-spinning documentation of how Vatican immunity shielded Nazi war criminals from just punishment--and unwittingly aided the Communist cause. Aarons is an Australian expert on Nazi fugitives; Loftus (The Belarus Secret, 1982) is the former chief prosecutor of the Justice Department's Nazi War Crimes Unit. Vatican accommodation of Nazi escapees is well known. Less known is that by 1944 Soviet intelligence had penetrated German intelligence and was using the Vatican, which was smuggling tens of thousands of Nazis to Argentina and elsewhere via diplomatic immunity, to infiltrate the Nazi escapees with large cadres of Communist spies. Similarly, Red spies joined the German scientists being swept off to Britain and America immediately after the war (without standing trial for war crimes); thereafter, the Soviets were privy to atomic secrets firsthand. Much of this activity, according to the authors, sprang from an episode in which Papal Nuncio Eugenio Pacelli (later Pope Pius XII) was attacked by Communists in Munich on May Day 1919 and became a fervent, lifelong anti-Communist. Thus came about his ties with the Nazis, who during the Nazi occupation of Italy threatened the Vatican's very survival. Referring to the infiltration of British intelligence at its top levels by Soviet spies, Aarons and Loftus proclaim that ``behind the Nazis were the Vatican, behind the Vatican were the British, behind the British were the Communists.'' One old spy, though, told the authors, ``Forget the Communists. Trace the money.'' Doing this, they report briefly--perhaps as a teaser for their promised follow-up book--on clever international banking concerns outwitting WW II politicians, militarists, and intelligence services for their own aggrandizement. Much that is new, all of it disturbing.