As "The Sicilian Defence" begins, we see a teenager, Harriet Farmer (Jo Woodcock) leaving her father (Richard Lumsden) a note and running away, into the woods. She's about to meet her boyfriend, Finn (Royce Pierreson), and elope.
Something happens at the rendezvous point; Harriet is hit and left in a coma. No one has seen Finn, who apparently left town.
A year later, the Bishopwood Chess Tournament is taking place at the time that Harriet wakes up with amnesia. Then the chess club president, Edward Stannington (Nicholas Rowe) is murdered, leaving his aunt Vivian everything.
On investigation, Barnaby finds out that Stannington was the illegitimate father of a young chess genius, whom he wants nothing to do with. Also, Stannington's rival, Alan Robson, Finn's father, has created a computer chess game and Stannington wants to discredit him.
The list of enemies continues. Arthur Potts, an unhappily married man, wanted Stannington to invest in his faltering business, but he was turned down.
Then Harriet's father is murdered and Dr. Laura Parr and Barnaby try to jog Harriet's memory by taking her into the woods. Her memory finally returns. A killer is exposed, and there's a surprise in store for the village.
The Sicilian Defense is a chess move, normally a starting move, and not a particularly unique one.
This was a good episode. Neil Dudgeon doesn't bother me any longer but I don't feel he adds anything either.