The Alchemist's Secret

Father Brown uncovers secrets, hypocrisy and murder at a finishing school for young ladies. Much to the disapproval of Mrs McCarthy, Father Brown attempts to support newly-single mother Nell Winford - but is unable to find her anywhere to stay.

The unexplained death of an unidentified man in St Mary's graveyard calls for investigation, but both Father Brown and Inspector Mallory have disappeared without a trace.

When Mallory's pursuit of a fugitive ends in disaster, a familiar face returns to hunt the culprit. Alan Tylett, suspected of killing a police officer, is seen near Kembleford - and Inspector Mallory is determined to catch him no matter the risk. After Sergeant Goodfellow is shot, Mallory reluctantly asks for the help of Father Brown. With Mallory in hospital, Divisional Chief Superintendent Len Blaisen takes charge - whilst his son Constable Colin Blaisen is more interested in seeing his fiancee Alice Bonham, who also happens to be Goodfellow's nurse.

Suspicions are aroused when the holiest house in Kembleford is linked to the death of a wanton woman. Mrs McCarthy is spending a lot of time with charming and devout Patrick O'Leary and is thrilled when Patrick's niece Maria Harley invites her to dinner. But Patrick's maid Francesa Chase and her son George are not happy with their new guest. Bunty delights in encouraging Mrs McCarthy's new relationship. Meanwhile the unpredictable Angelica Evans has a secret that she will no longer keep, but dies in the church before she can tell all.

Tensions rise to deadly levels when a performance troupe of anarchists arrive in Kembleford. An anarchist troupe are performing at Clegg Farm intent on starting a revolution. Mrs McCarthy is not impressed, but Bunty is inspired. Off-stage the suspicions of Farmer David Clegg are aroused by the relationship between his wife Sally and enigmatic performer Titan Stark. When the troupe's writer is found dead in a locked outhouse Father Brown is not convinced that suicide is the cause.

The Kembleford Ramblers annual outing takes a tragic turn when the local Lord is found strangled. In the name of community togetherness Inspector Mallory and Sergeant Goodfellow are joining some local ramblers, as is Father Brown, Mrs McCarthy, and, much to her horror, Bunty. Leading them all is Cathy Fawlter whose husband Norman is giving Goodfellow some birdwatching advice - but Mrs McCarthy is more interested in the gossip surrounding Cathy and the local odd-job man Randall Jones.