In the quiet confessional of a Catholic church, parishioners come to unburden their souls before God. Or, that's the idea. The Professor uses it as a vehicle for his militant atheism; Roy has permanently mistaken the confessional for a Caffe Nero; the rest are mostly there for the free wine. Faced with a bewildering series of evidently unhinged parishioners, their long-suffering priest, Father Matthews, tries valiantly to get them to stick to the point.

But, whatever the challenges, Father Matthews is adamant that nothing will deter him from his fervent intent: to shepherd his flock to the gates of Paradise. Even if sometimes he would gladly leave some of them behind.

With the listener never leaving the confessional in which each episode's action takes place, Mea Culpa provides a glimpse into the strange private lives of an eclectic London community, all of whom just want someone to talk to about their problems.