KEEPERS OF THE KEYS
by Wilton Wynn
Random House; 278 pages; $18.95
When Pope Pius XII died in 1958, his aide and preferred successor, Archbishop Giovanni Battista Montini, was ineligible for the papacy because he was not a Cardinal. As a stopgap, the Cardinal-electors turned to the apparently innocuous Angelo Giuseppi Roncalli, 76. Roncalli, of course, became Pope John XXIII, whose Vatican Council set in motion epochal reforms in the church. But Montini, who was made a Cardinal by John, finally got his turn after John died in 1963, and it was his dogged bureaucratic talents, as Pope Paul VI, that...