Case file · Series 25, Episode 1 · Season 25, Episode 1
Treasures of Darkness
A riverbank discovery intensifies a rivalry between mudlarking groups before a suspicious drowning revives an old disappearance.
Verified filming locations
Every filming site currently documented in this Casebook file is listed here. The published evidence does not establish a complete production itinerary.
- St John the Baptist Church · Little Missenden, Buckinghamshire
The church appears as the parish church of Goldworthy's unnamed neighbouring village.
Site guide → Filming source ↗ - The Red Lion · Little Missenden, Buckinghamshire
The pub is presented on screen as The Speckled Trout.
Site guide → Filming source ↗ - The Manor House · Little Missenden, Buckinghamshire
The property supplies the exterior of Alice Gideon's home.
Site guide → Filming source ↗
Map lookup by place name. A private house’s exact address is not marked.
Selected episode credits
Treasures of Darkness cast
These selected cast entries link to their published profiles. They do not include every name shown in the end credits.
Fiona Dolman
Isabel Shaw
Camilla Marie Beeput
Tony Way
Poppy Miller
Killian Coyle
Ben Jones
Adrian Rawlins
Jayde Adams
Gary Wilmot
Kate Anthony
Jude Akuwudike
Manpreet Bachu
Varpu Kronholm
Francesca Cozier
The 60-second case card
Should I watch this one?
A traditional village mystery in which objects recovered from the river disturb the stories people have told for years.
- Best for
- Mudlarking · River treasure · Old disappearance
- Mood
- Classic
- Team
- DCI John Barnaby with DS Jamie Winter
- 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 traditional village mystery in which objects recovered from the river disturb the stories people have told for years.
Two rival groups arrive at the same Goldworthy riverbank in search of historic objects, and an argument over a newly found ampulla sets the tone. When Jonny Hoxham is discovered near the jetty, what first resembles an accidental drowning is revealed to involve a deliberately concealed hazard.
At the same time, Lucy Weaving returns to ask what happened to her aunt Jessica, who vanished after breaking with her family. A bicycle recovered from the water draws the present investigation towards that older absence and makes Lucy herself a target.
Break the seal: reveal the finding
The new deaths and threats are tied to Jessica's disappearance, the relationships surrounding her departure and the evidence that the river has finally returned.
More episode detailsProduction, cast, deaths and filming information
Credits, context and checked facts
Production and cast
- TV series
- Series 25
- Episode number
- Episode 1
- Written by
- Julia Gilbert
- Directed by
- Paul Gibson
- Listed transmission date(s)
- 8 December 2025
- Reported filming period
- March–April 2025
- Detective
- DCI John Barnaby
- Partner
- DS Jamie Winter
- Pathologist
- Dr Fleur Perkins · Annette Badland
- Principal setting
- Goldworthy
- Casebook tone
- Classic
Check the credits, then follow the source trail for production and filming details. Counts below describe this archive’s records.
The fictional setting and the real filming sites are separate pieces of information. The location desk currently connects it to 1 broader filming area and 3 exact on-screen site identities.
Credits and archive connections
- Writer credits7 episodes credited to Julia Gilbert
- Director credits3 episodes directed by Paul Gibson
- Release positionCase 141 of 144
- Story characterClassic · Mudlarking · River treasure
- Location evidence3 exact screen-use matches
The village church, Red Lion pub, manor house and Village Road supply Goldworthy locations, including the fictional Speckled Trout.
The case uses mudlarking finds and a recovered bicycle as separate physical routes into the village's past.
Sources for the production file
Published episode chronology and credits ↗Official ITV programme page ↗Filming-location reference index ↗The chronology is the reference for the credits shown here. A programme homepage does not independently verify a filming date or every production detail. Where multiple transmission dates are listed, territory attribution needs checking. Story, teleplay and adaptation distinctions require the original credit wording; links to external synopses may reveal plot details.
The performers behind this case
Core cast
Actor profiles for the detective, investigating partner and pathologist credited to this episode.
Neil Dudgeon
John Barnaby · Detective Chief InspectorAn English actor whose television work before Causton included Piece of Cake, The Mrs Bradley Mysteries, Messiah and the sitcom Life of Riley. He also appeared in Midsomer Murders years earlier as a different character in Garden of Death.
- Messiah
- Life of Riley
- The Mrs Bradley Mysteries
Nick Hendrix
Jamie Winter · Detective SergeantAn English actor trained at the University of Exeter and RADA. His theatre work includes the National Theatre, Old Vic and West End, while his screen credits include Black Mirror, Marcella, The Crown, Legend and Suffragette.
- Black Mirror
- Marcella
- The Crown
Annette Badland
Dr Fleur Perkins · Police pathologistAn award-winning English actor with an extensive career in theatre, television, film and radio. Her many recognisable roles include Doctor Who, EastEnders, Outlander, Bergerac and pub landlady Mae in Ted Lasso.
- Ted Lasso
- Doctor Who
- EastEnders
Portraits are used only where a reusable licence or public-domain release has been verified. Publicity stills and stock photographs are not copied into this independent guide.
Forensic desk
Dr Fleur Perkins
- Credit
- Resident pathologist
- Played by
- Annette Badland
Fleur pairs forensic certainty with dry humour and a magnificently low tolerance for Midsomer nonsense.
Meet the Casebook pathologists →Spoiler-controlled deaths desk
Deaths recorded in this case
3 people die in this case, according to the linked death record.
Break the seal: reveal the death ledger
- Jonny Hoxham
Murder · Drowning
Performer check- Jonny Hoxham: Ben JonesThe earlier synopsis-derived ledger expanded the victim’s name to Jonathan Hoxham; the published cast record supports Jonny Hoxham, used here.
- Rufus Coulter
Murder · Other recorded death
Performer check- Rufus Coulter: Gary Wilmot
- Jessica Clissold
Murder · Other recorded death · historical or before the main case
Performer check- Jessica Clissold: not listed in the current published cast recordThe historical victim is named in the episode synopsis, but no Jessica Clissold performer appears in the current published cast record; Young Jessie is a different credited character, so no identity is inferred.
Break a second seal: reveal the verified killer
Verified killer
Alice GideonAlice killed Jessica 'Jessie' Clissold during a confrontation years earlier and hid her body, then killed Jonny Hoxham after he saw her checking the burial place and Rufus Coulter when he recovered evidence. She later tried to kill Lucy Weaving; William Gideon's confession was false and intended to protect Alice.
Verified motive
Alice's childhood abandonment made her desperate for safety and terrified of being left again. She killed Jessie during the confrontation when Jessie threatened to expose their relationship after Alice abandoned their escape plan, then killed Jonny and Rufus to keep that death and the ring hidden and attacked Lucy when her investigation threatened the life Alice had built with William.
Real place → fictional identity
What was filmed where?
St John the Baptist Church
Used as: The church appears as the parish church of Goldworthy's unnamed neighbouring village.
Representative photograph of the real filming location; the exact camera angle or building may differ.The Red Lion
Used as: The pub is presented on screen as The Speckled Trout.
Representative photograph of the real filming location; the exact camera angle or building may differ.The Manor House
Used as: The property supplies the exterior of Alice Gideon's home.
Representative photograph of the real filming location; the exact camera angle or building may differ.Sources support the listed site uses; they do not establish every filming location in an episode.
Wider filming areas