© ITV/Mark Bourdillon

DCI Barnaby is adapting to life with baby Betty when he is interrupted by a phone call from DS Nelson. Artist Suzie Colebrook has been electrocuted by a booby-trapped roulette wheel sent in the post shortly after she discovered a break-in at her home.


Suzie illustrated the Jed Dagger detective novels written by late Luxton Deeping author George Summersbee. She was also the executor of George's estate. The murder comes as a local crime festival is about to unveil a newly discovered Dagger story - and her publisher husband Niall seems more concerned that the priceless manuscript has been stolen than that his wife has been murdered.


The festival itself is a hotbed of tension between George's daughter Bella, a bookshop owner and sole beneficiary of her father's will, and her mother Jeanie, while Bella's partner Rob Mead is stressed about money. Organiser Maggie Markham is in her element promoting her GP husband Nick Summersbee's memoirs about his famous brother.


Nelson discovers the electrocution mirrors a plotline in the first Dagger novel 'The Wheels of Justice', except that in the book roulette wheels are posted to two victims. Many villagers would have loved to get their hands on the manuscript, including obsessive fan Curtis Braylesford and big time publisher Miles Rattigan, while Maggie claims Jeanie hated Suzie for having an affair with George.


A second deadly roulette wheel is traced to the house of retro specialist Cecilie Peterson 30 miles away, but the police get there too late. At first there is no obvious connection between the victims but Barnaby spots Suzie's original artwork for 'The Wheels of Justice' on the wall. Curtis' aunt Audrey demands money from Rob while Jeanie tells Barnaby her husband died in a boating accident. She is convinced the missing manuscript is fake, while Maggie and Nick offer a reward for its safe return.


Phone records reveal both victims knew Bella. As forensics reveal Suzie's break-in was staged, Bella reveals Suzie wanted Miles to publish the new book rather than Niall, giving the dead woman's husband motive to steal it and possibly kill her. But then police find Niall crushed to death under his printing press.


At an exhibition of Suzie's art, Rattigan tells Barnaby that George had huge debts. Nelson follows gallery owner Vincent Treaborne to the bookstore where an illicit game of poker is taking place. The stakes are high - and Audrey wins Rob's share of the bookshop. Barnaby makes a shocking discovery that George is alive and had been living with Cecilie. Meanwhile Curtis stumbles upon George himself and arranges for Bella to meet her father in the woods. But when she gets there they are chased, and George is stabbed to death with a dagger. Kate reveals that the murderer is left-handed.


Jeanie learns that her husband is dead - not years ago but only hours ago, while everyone converges on the bookshop where Nick is launching his memoirs. Can Barnaby find who really died in the boating accident, locate the manuscript and unmask the killer?