Armitage Brown of MI5 still chafes over one suspect that got away from his Operation Large Scotch mission, Mhairi McClure and he wants to rectify that. She, on the other hand, chafes under the 'protection' she endures in the Vatican. When she escapes, taking with her a great deal of intel on some shady dealings members of the Church are involved in, the number of people wanting her head grows considerably.