Based on the short stories by G. K. Chesterton, Father Brown is a Roman Catholic priest and amateur detective.
Lord of the manor Colonel James Bohun, a sadistic bully and chauvinistic womaniser, is widely loathed in his small English village. Despite being married, he openly flaunts his conquests and shows only disdain for the beliefs of his brother Wilfred, the local Anglican vicar. When James is found in the churchyard with his skull smashed by a single blow from a blacksmith's hammer, Father Brown, a guest of the vicar's, brings his sleuthing skills to the case.
Colonel Arthur Druce is unhappy with his son Harry for his frivolous behaviour and his daughter Janet for her choice of a French doctor as fiancé. He summons his lawyer and changes his will, only to be stabbed to death shortly thereafter in the estate's summer house. Houseguest Father Brown assists in tracking down his late host's killer.
When American archaeologist Gerald Smaill uncovers a golden Byzantine cross in cave in Asia Minor, a disembodied voice threatens death. En route back to England via cruise, he receives further threats and confides in fellow traveller Father Brown. A secret crypt beneath a Dover church has been recently uncovered containing the body of a 13th-century bishop mummified in Egyptian fashion, along with a similar golden cross. Smaill, Brown, and several passengers investigate the find and risk the curse that accompanies it.
Aging, blind dowager Miss Dorothy Ammersly, an advocate of equality for women in the workplace, has consigned her fortune to her niece, successful businesswoman Pauline Stacey. Unfortunately, Pauline is not as astute on judging character and has fallen under the spell of ex-convict Kalon, who has reinvented himself as the high priest to Apollo, the sun god. Pauline makes out her will, ignoring her sister and naming him as her sole heir, before falling to her death. Having been in close proximity, Kalon becomes a suspect, but he has an impeccable alibi provided by one Father Brown.
Scottish noble Sir Aaron Armstrong is a reformed alcoholic who advocates temperance and hires dipsomaniac Patrick Royce as his secretary on condition he give up the sauce. When Armstrong learns that his daughter Alice plans to marry Royce, he ignores Royce's fifteen months of sobriety and discharges him. Not long after, Armstrong is found with a broken neck outside a high window on his estate, the apparent victim of foul play. Father Brown assists Inspector Gilder in investigation.
Brilliant but controversial conservative jurist Sir Arthur Travers is found murdered by gunshot in his estate garden. As he was murdered outdoors, the police are unable to explain how an indoor mirror in his house came to be shattered. Osric Orm, a Fabian Socialist known for his radical views, is charged, but Father Brown instinctively believes him innocent and sets out to find the real killer.
Wealthy Essex landowner Augustus Aylmer confesses to Father Brown that fear of his impending death has caused him to dabble in the occult, enabled by John Strake, his adopted son. Aylmer had made Strake his heir because he feels his natural sons aren't needy, but ultimately realises his error and disinherits the necromancer. When two of his sons die under unusual circumstances, Brown suspects foul play.
Mundon Mandeville, who runs a reviled repertoire theatre troupe, is murdered inside a windowless room. Everyone has an alibi. Father Brown is there as a favour to Flambeau to consult a 17-year-old into returning home to her worried parents who don't realise she has lied about her age in order to follow her dreams as an aspiring actress.
While staying at a country hotel, Father Brown becomes involved in the murder of an unpopular local man found stabbed in the hotel bar. As suspicion falls on several of the guests, Father Brown and Flambeau investigate the circumstances surrounding his mysterious death.
Father Brown is staying with an old friend, a former jewel thief who retired to beekeeping in the country. Someone has been using his m.o. to commit a rash of local robberies, and when he is found shot, the local police inspector assumes he had returned to his former profession. Brown sets about clearing his name.
Christabel Carstairs has inherited the estate of her late, well-to-do father with the exception of his celebrated collection of Ancient Roman coins, which go to her elder brother. As an art student, she becomes infatuated with a male model and impulsively steals a coin from the collection as she believes its likeness of Augustus Caesar Augustus resembles the young man in question. When a blackmailer tries to coerce money from her to keep the theft secret, she tuns to Father Brown and Flambeau for help.
A paranoid millionaire becomes obsessed with a priceless early Christian chalice and wins it at auction. He lives with it in an impervious citadel, but is killed by an arrow in the neck. The irrepressible Father Brown must sift through a plethora of red herrings to find the killer and the motive.
Father Brown is staying at a beautiful French mansion with an assortment of red herrings when a decapitated body is discovered in its enclosed, inaccessible garden. Brown sorts through a variety of puzzling clues, only for the verdict to be simple but incredible.
