When the notorious thief Flambeau declares his intention to steal a valuable blue cross from the church, Father Brown, against the advice of Valentine, decides to take it to safety to Newbury abbey by train. He meets a trio of fellow passengers, one of which he is sure is the thief but his efforts to flush him out lead to the theft of the cross. Facing dismissal for his rash action the Father agrees to meet with Flambeau and do a deal to return the artefact.

Professor Ambrose is abducted after sending his friend Father Brown an ancient prayer book which supposedly can locate the long disappeared Lannington rosary, said to hold healing powers. Aided by Lady Felicia's chauffeur Sid the priest uses the book to find clues which will lead him to the rosary. There is a deadline as a ransom note arrives, informing the father that the rosary must be delivered to save his friend's life whilst the quest is complicated by the arrival of supposedly reformed criminal Flambeau, who claims he is working as a mercenary for the Papacy to find the relic. And then there is a third party, the actual kidnapper, whom Father Brown must expose.

The local art gallery has the priceless painting 'The Judgement of Man' on loan from the Vatican and curator Binkie Cadwallader is flattered to be interviewed by the glamorous reporter Rebecca Himmelbaum. Father Brown is convinced that Flambeau is out to steal it and is proved right when Lady Felicia's gallant new American friend Chip Corner turns out to be the thief in disguise. But there is another miscreant out to steal the painting and Rebecca has her own agenda, to punish Binkie for a wartime betrayal.As a result Father Brown and Flambeau enter into a bizarre alliance and Flambeau proves to be more principled than the priest thought.

Father Brown must help Flambeau in stealing the Pope's gift to the Queen.

Father Brown suspects an ulterior motive is at play when his old adversary Flambeau is incarcerated for murder.

Father Brown reads that Flambeau has been killed in Italy before setting off to Gloucester where the Iron Crown of Lombardy, made from a nail from the Crucifixion, is housed. He is approached by a woman claiming to be Flambeau's widow but a key Flambeau sent him has been stolen and Father Brown believes it is connected to the intended theft of the Iron Crown. A chance meeting on a train proves him right and he must stop the theft - at the risk of his life.

Lady Felicia's diamond is stolen by a Russian who wanted to buy it, but she refused. Father Brown calls in Hercule Flambeau to steal it back from him. Flambeau also empties out the Russians safe and double crosses them.

Flambeau seeks Father Brown's help to get rid of an unwanted rival.

Father Brown joins forces with Flambeau to search for a lost treasure in a 15th-century castle.

Lady Felicia and her husband Monty host a lavish masked ball counting down to 1954. However, their plans are ruined when the Minster of Defence is murdered by a masked figure. With the estate locked down and a killer in the midst.

Chief Inspector Sullivan pays Father Brown a visit to warn him that Hercule Flambeau is on the run and wanted for a series of brutal murders.

Chief Inspector Sullivan pays Father Brown a visit to warn him that Hercule Flambeau is on the run and wanted for a series of brutal murders.

Lady Felicia's diamond is stolen by a Russian who wanted to buy it, but she refused. Father Brown calls in Hercule Flambeau to steal it back from him. Flambeau also empties out the Russians safe and double crosses them.

Father Brown reads that Flambeau has been killed in Italy before setting off to Gloucester where the Iron Crown of Lombardy, made from a nail from the Crucifixion, is housed. He is approached by a woman claiming to be Flambeau's widow but a key Flambeau sent him has been stolen and Father Brown believes it is connected to the intended theft of the Iron Crown. A chance meeting on a train proves him right and he must stop the theft - at the risk of his life.

Flambeau seeks Father Brown's help to get rid of an unwanted rival.

Father Brown suspects an ulterior motive is at play when his old adversary Flambeau is incarcerated for murder.

Father Brown joins forces with Flambeau to search for a lost treasure in a 15th-century castle.

Father Brown must help Flambeau in stealing the Pope's gift to the Queen.

The local art gallery has the priceless painting 'The Judgement of Man' on loan from the Vatican and curator Binkie Cadwallader is flattered to be interviewed by the glamorous reporter Rebecca Himmelbaum. Father Brown is convinced that Flambeau is out to steal it and is proved right when Lady Felicia's gallant new American friend Chip Corner turns out to be the thief in disguise. But there is another miscreant out to steal the painting and Rebecca has her own agenda, to punish Binkie for a wartime betrayal.As a result Father Brown and Flambeau enter into a bizarre alliance and Flambeau proves to be more principled than the priest thought.

Professor Ambrose is abducted after sending his friend Father Brown an ancient prayer book which supposedly can locate the long disappeared Lannington rosary, said to hold healing powers. Aided by Lady Felicia's chauffeur Sid the priest uses the book to find clues which will lead him to the rosary. There is a deadline as a ransom note arrives, informing the father that the rosary must be delivered to save his friend's life whilst the quest is complicated by the arrival of supposedly reformed criminal Flambeau, who claims he is working as a mercenary for the Papacy to find the relic. And then there is a third party, the actual kidnapper, whom Father Brown must expose.

When the notorious thief Flambeau declares his intention to steal a valuable blue cross from the church, Father Brown, against the advice of Valentine, decides to take it to safety to Newbury abbey by train. He meets a trio of fellow passengers, one of which he is sure is the thief but his efforts to flush him out lead to the theft of the cross. Facing dismissal for his rash action the Father agrees to meet with Flambeau and do a deal to return the artefact.