Midsomer Murders is one of the best detective shows, in my opinion. Unfortunately, season 12 came out rather weak, despite the wonderful Jason Hughes and his character Ben Jones. In fact, I can't give any episode a solid 10 ("The Dogleg Murder "is quite atmospheric but not serious enough,"The Glitch" is a bit boring, "The Creeper" is actually good for everyone, but the killers are absolutely disgusting), and three episodes ("Secret and Spies" and especially "Great and Good" and "The Black Book") were particularly bad.
"Small Mersies "is an ambiguous episode, brilliant in the first viewing, but somewhat disappointing in the second (in fact, this is the problem of many maniac films, even those as brilliant and exceptional as "Driven to Distraction" from Inspector Morse). On the one hand, it is quite interesting, atmospheric, there are several colorful characters, and the final conversation with the killer is gorgeous. On the other hand, from the second viewing, the episode becomes somewhat boring, because the denouement is already known and all the tension and atmosphere subsides.
The acting performances are pretty good, especially Olivia Colman stands out in my opinion.
In General, quite an interesting, although not the best episode. 9/10