Alec Guinness is fun to watch as G.K.Chesterton’s amateur detective Father Brown. He’s trying to keep an art thief out of the hands of police until he can save his soul.
A meeting is taking place in Rome. Father Brown’s 12th century cross is going to be a part of it. A police escort has been arranged to get it there safely. In just a few minutes Father Brown says he’s thought of three ways it can be stolen. Everyone is afraid the master jewel thief Gustave Flambeau (Peter Finch) will make a try for it. Not helping matters is that he is a master of disguise.
Father Brown proposes carrying the cross himself. He feels it’ll be too obvious a place among a group of priests and thereby a lot safer. He wraps it in brown paper and also makes up a similar package and carries them both aboard a ship to the first stop, France.
At an outdoor cafe in France Father Brown is sitting at a table with Flambeau. He uncovered his identity earlier after riding on a train with him. The French police are watching them. Father Brown proposes making their escape on a tourist bus to the catacombs.
Once inside Flambeau says he has the cross. He switched parcels at the cafe. He takes off. Father Brown enlists the help of parishioner Lady Warren (Joan Greenwood). He wants her to auction of a valuable chess set. He figures Flambeau won’t be able to resist trying to grab it. He’s right. Despite all the security Flambeau wins again.
Father Brown refuses to give up. A bottle of wine helps him track Flambeau down. The movie drags in spots but Father Brown is an appealing eccentric character who takes impromptu judo lessons and has his own unique way of doing things that usually get him in hot water with the arch bishop.