The show needs to stop. It has completely lost any connection to the Father Brown series of books, and has turned into a foul-minded, lurid, mean-spirited soap opera with bad direction, overstuffed sets, and characters devoid of human authenticity. This episode was about the worst. Grand guignol imagery and violence, a clot of murders beggaring sense, long talky scenes of low-end psychobabble, sound effects of vomiting - the production team seems to consist of misplaced cranks determined to savage their source.
If this "updating" is thought to be required, again, the question is why fo they bother? Cynicism? Sticking it to what they see as an outmoded religious source, represented by a daddy priest? Pressure from someone higher up?
It doesn't matter. The show, with enough budget and talent for a first-class effort, is now just another example of the usual trash.