Robert Harris writes intelligent thrillers based on historical events, from the rise and fall of the Roman Empire to the tumultuous 21st century. Some of his notable books include “Enigma,” about the breaking of Germany’s secret code in World War II, and “Fatherland,” a scary and suspenseful alternate history based on what could have happened if the Nazis had won World War II.

“Conclave” opens when a pope who bears a marked resemblance to the current leader of the Roman Catholic Church, Francis, has died. The College of Cardinals is called to select a successor, but from the very first it’s clear that the Vatican is rife with secrets, any one of which could derail the election.

One leading contender may have been stripped of his offices by the pope right before the pontiff died. There’s a distraught nun with a secret, and a mysterious cardinal no one has heard of who suddenly shows up.

This might be the ultimate locked-room mystery; the cardinals are sequestered and can’t emerge until they elect a successor. What happens? Harris intends to keep the reader guessing, and he does a fine job of it. Read it and find out.