We do always enjoy the customary fare from Vera, along with her current crew of Aiden, Kenny, Jac, and of course Malcolm (but the late-lamented Billy was an absolute stand-out). Some plots are more engaging than others, and of course it wouldn't be a mystery if it was the most obvious suspect wot dun it!
But usually we have a few 'innocent bystanders', mingling in there with all the dubious characters. We have people who knew the victim, but did no wrong. We see someone who may have disliked the victim, or maybe who stood to inherit, but had no hand whatever in their decease, and no guilty secrets. We even have people whom we find out have told the truth at all times!
There was no such person in this episode. Every single person in this entire nest of vipers had something to hide, or was complicit in covering for someone who did, and lied to Vera in order to achieve this goal. Every single person!
This became a major plot weakness, and I think only 6/10 is merited.