Father Brown tries to transport a historically important cross to Rome engaging in battles of wits and faith with a thief and pursuing policeman. The thief, named Flambeau (Finch), is a master of disguise and is elusive, as Father Brown pursues him and tries to convince him to abandon his criminal career.　(🔮)　During the making of the film, Alec Guinness was mistaken by a small boy for an actual priest. This episode appears to have played a part in Guinness's later conversion to Roman Catholicism.