Wisdom's Way / (The case of the) Rhubarb Crumbles

A series of poisonings are reported to the police in a very short space of time. They involve two couples, two fifteen year old boys, and a reclusive neighbour of Matthew Wisdom. Two people die as a result. There seems to be no direct link or connection between any of the victims, and the police are at a loss when it comes to catching the culprit. Their attention is drawn to three elderly ladies who operate a church cake stall. Visits to them to exclude them from the police enquiry are marred by the jobsworth gatekeeper. Vengeance may be sweet, but where to the 'Bunny Cakes' come in?