It's now 1955 and Chief Inspector Sullivan and Mrs. Devine have grown closer since we saw them last, something that hasn't escaped the notice of Father Brown and Brenda. With a food fayre to die for, a real-life crime at a crime writing festival and a village rivalry that turns deadly, there's plenty for the gang to be busy with. And when his old friend Sister Boniface is implicated in a murder at an arts and craft fair, Father Brown must prove her...

A tumultuous but enduring relationship between two men across many years of laughter, heartbreak and rage. It is also the story of real-life best friends who turn their profound connection into a rich, humane and frequently uproarious film about the boundaries, or lack thereof, in all close friendships.