"SINS OF COMMISSION"
In 2004, Causton Police Inspector Tom Barnaby investigated a series of murders at the 12th annual Maplin Literary Prize festival in the village of Midsomer-St. Michael's. The Maplin Prize was endowed in memory of local author Conor Maplin, who passed away in 1992 at the age of 70.
His widow, somewhat younger than he was, was Grace Maplin and she was one of the executors/trustees for the endowment. Despite the crimes committed during that festival weekend, Grace was still able to see the awards ceremony to its successful - if highly controversial - conclusion.
From this point on, it's all Toobworldian conjecture.....
For the Maplin Prize festival the following year, Grace invited her sister Christine to travel to Midsomer-St. Michael's and attend the ceremonies. It would be a chance for them to catch up, since Christine spent most of her time pursuing a career in jurisprudence in London.
In Toobworld, there is no such thing as coincidence, and yet "by chance", Christine took the train from London on which she met a cousin to Inspector Barnaby who was also traveling to Causton in Oxfordshire in order to visit his cousin Tom. (This cousin was not John Barnaby, however.)
Barnaby's cousin and Grace Maplin's sister Christine hit it off and ended up spending most of that 2005 weekend with each other rather than with the family members they were supposed to be visiting.
By the end of the year, they were married.
The Barnabys reside in London where Christine Barnaby is a sitting judge in Chambers.
Stella Gonet played Grace Maplin and Judge Christine Barnaby.....