Case file · Series 17, Episode 1 · Season 17, Episode 1
The Dagger Club
A newly discovered crime manuscript attracts collectors, gamblers and a killer apparently following its methods.
The 60-second case card
Should I watch this one?
A knowingly bookish mystery about authorship, ownership and the dangerous price placed on a dead writer's name.
- Best for
- Crime fiction · Lost manuscript · Collectors
- Mood
- Classic
- Team
- DCI John Barnaby with DS Charlie Nelson
- Spoiler guidance
- Read the premise freely; open the marked sections only after watching. Check the linked provider advisory for further viewing information.
Why it matters
A knowingly bookish mystery about authorship, ownership and the dangerous price placed on a dead writer's name.
Luxton Deeping's crime festival is electrified by news of a newly discovered manuscript from the late novelist George Summersbee. The document is stolen, and a woman is killed by a roulette-wheel trap that appears to turn the writer's fictional ingenuity into a real murder method.
Barnaby and Nelson investigate Summersbee's family, publishers, collectors and rivals while the festival trades eagerly on his reputation. Questions about who owns the manuscript gradually give way to the more important question of who actually created the work on which that reputation rests.
Break the seal: reveal the finding
Who was the killer in The Dagger Club? (spoiler)
The manuscript is both valuable bait and evidence of concealed authorship. Barnaby's solution depends on separating George Summersbee's public legend from the identities and creative work hidden behind his name.
More episode detailsProduction, cast, deaths and filming information
Credits, context and checked facts
Production and cast
- TV series
- Series 17
- Episode number
- Episode 1
- Written by
- Chris Murray
- Directed by
- Alex Pillai
- Listed transmission date(s)
- 28 January 2015
- Reported filming period
- April–May 2014
- Detective
- DCI John Barnaby
- Partner
- DS Charlie Nelson
- Pathologist
- Dr Kate Wilding · Tamzin Malleson
- Principal setting
- Luxton Deeping
- Casebook tone
- Classic
Sources accompany the production credits and filming links.
Fictional settings and real filming places are listed separately. Filming links include 1 mapped area; 3 exact sites.
Credits and archive connections
- Writer credits6 episodes credited to Chris Murray
- Director credits7 episodes directed by Alex Pillai
- Release positionCase 101 of 144
- Story characterClassic · Crime fiction · Lost manuscript
- Location evidence3 exact screen-use matches
The episode builds its case around a literary festival, a lost manuscript and people attempting to profit from a famous crime writer.
The old courthouse in Long Crendon appears as the episode's village bookshop.
Sources for the production file
Published episode chronology and credits ↗Official ITV programme page ↗Filming-location reference index ↗Credits follow the linked chronology. Dates can differ between territories. Consult original credits for story, teleplay and adaptation wording. External synopses may contain spoilers.
Selected episode credits
The Dagger Club cast
These selected cast entries link to their published profiles. They do not include every name shown in the end credits.
Fiona Dolman
Simon Kunz
Lia Williams
Una Stubbs
James Lance
Ed Birch
Adam Kotz
Oona Kirsch
Georgia Taylor
Charlotte Cornwell
Kobna Holdbrook-Smith
Timothy Watson
Howard Ward
Grant Russell
Liberty Mills
The performers behind this case
Core cast
Follow the cast links for full actor and character guides.
Neil Dudgeon
John Barnaby · Detective Chief Inspector- Messiah
- Life of Riley
- The Mrs Bradley Mysteries
Gwilym Lee
Charlie Nelson · Detective Sergeant- Bohemian Rhapsody
- The Great
- Jamestown
Tamzin Malleson
Dr Kate Wilding · Police pathologist- Teachers
- Bodies
- Unforgotten
Image credits identify the licence used. No programme publicity stills are reproduced.
Forensic team
Dr Kate Wilding
- Credit
- Resident pathologist
- Played by
- Tamzin Malleson
Spoiler-controlled deaths
Deaths recorded in this case
4 people die in this case, according to the linked death record.
Break the seal: reveal the list of deaths
- Suzie Colebrooke
Murder · Electrocution
Performer check- Suzie Colebrooke: Oona KirschThe earlier synopsis-derived list printed Colebrook; the published cast record supports Colebrooke, used here.
- Cecilie Petersen
Murder · Electrocution
Performer check- Cecilie Petersen: Liberty MillsThe earlier synopsis-derived list printed Peterson; the published cast record supports Petersen, used here.
- Niall Colebrooke
Murder · Crushing
Performer check- Niall Colebrooke: Howard WardThe earlier synopsis-derived list printed Colebrook; the published cast record supports Colebrooke, used here.
- George Summersbee
Murder · Stabbing or impalement
Performer check- George Summersbee: Grant Russell
Break a second seal: reveal the verified killer
Who was the killer in The Dagger Club? (spoiler)
Nick SummersbeeNick killed Suzie Colebrooke and Cecilie Petersen to make his brother George suffer, then killed Niall Colebrooke to stop the recovered manuscript being published and finally stabbed George in the woods. Nick had earlier helped George fake his death using the naturally deceased Mark Sampson's body; Maggie Markham stole the manuscript but was not one of the killers.
Verified motive
Nick resented spending his life in George's shadow and helped stage George's disappearance because he wanted rid of him. When George planned to return with another manuscript, Nick killed the women closest to him to make him feel loss, killed Niall to stop publication and finally killed the brother he blamed for years of humiliation.
Verified decisive clue
Archive case 101 · checked 25 September 2026Mark Sampson's body identified as George SummersbeeThe natural-death patient was identified as George with Nick's help, revealing that George was alive and still writing. His return and the new manuscript expose Nick's motive; Nick admits killing the women close to George, Niall and finally George. Maggie's staged burglary and theft of the manuscript are separate acts.
Real place → fictional identity
Where was The Dagger Club filmed?
Britwell Salome House
Used as: The country house becomes Jeannie Summersbee's home.
Court Lane house
Used as: A private house is used as the village art gallery.
The Old Courthouse
Used as: The medieval building appears as the Luxton Deeping bookshop.
Representative photograph of the real filming location; the exact camera angle or building may differ.Sources accompany the identified filming places.
Wider filming areas