Queen Brigitte II of Albion dies with no successor to take her place, leading to the possibility that a foreign power may take hold of the kingdom. Wanting to maintain equilibrium amongst the world powers, the Vatican sends Pope Alessandro XVIII, along with Sister Esther, to Albion, which in turn seeks to strengthen its ties with the Vatican. Colonel Mary Spencer and Count Virgil Walsh give Esther and the Pope a tour of the Ghetto, which lies underneath Londinium, the capital city of Albion. There, the advanced technology of Albion is created solely by the work of Methuselahs, who live peacefully with but isolated from the Terrans above them. During the tour, Virgil's sister, Vanessa Walsh, attempts to kidnap the Pope, who escapes with help from Esther. When she learns of what has happened, Cardinal Sforza asks Brother Petro and Sister Paula to assist Fathers Abel, Leon, and William Walter Wordsworth in finding and protecting Pope Alessandro XVIII, fearing that Cardinal Medici, who refuses to negotiate with vampires, will let him be killed and become a martyr.