The story is told primarily from Hubert's standpoint although the focus shifts at times to other characters. The clergy who are planning Hubert's alteration are nearly all portrayed unsympathetically, as worldly cynics concerned only with their own advancement. The only partial exception is the Anvil's family chaplain, Father Lyall, who resists signing the order for the alteration, although mainly out of rebelliousness and not because he thinks it is wrong to subject a young boy to this. He is a womaniser and has an affair with Hubert's mother, which predictably ends in tears and worse.
Perhaps understandably, there is not too much comedy in this book. What there is comes mainly courtesy of the Pope, John XXIV, a Yorkshireman with a vivid sense of his own importance who invariably refers to himself in the first person plural. Since, to his annoyance, "that bugger Innocent XVII" outlawed artificial contraception, His Holiness has tried to solve the problem of over-population by putting an contraceptive drug in the water supply, but the large number of birth defects that resulted has made this politically inadvisable. Another nice touch of humour comes from the appearance off-stage of people from our own reality in a different guise. There is a theologian named Ayer, for example, and we learn that Castel Gandolfo had been burnt in 1853 by 'a certain Percy Shelley, excommunicate English runaway and minor versifier'.
Hubert initially believes it is his duty to be altered, since both the Church and his fanatically devout father say it is. Later he changes his mind and seeks to escape to America with the help of the New England ambassador, with whom he has made friends. His attempt results in an unexpected (and medically improbable) dénouement.