A university professor is murdered. A head teacher mysteriously drowns after being poisoned. Then a triathlon produces a baffling case of mistaken identity.

Those are just some of the mysteries awaiting two unlikely detectives in Old Town Murders, a new six-part BBC crime drama that combines murder with the picturesque seaside surroundings of Tenby in West Wales.

Mark Lewis Jones and Steffan Rhodri lead the series as DI Glyn Walsh and DS Sion Dearden, two friends unexpectedly thrown together professionally and personally as a succession of increasingly unusual killings lands on their doorstep.

But the series is not intended to be purely about catching murderers.

Creator Matthew Barry describes it as a story about friendship, reinvention and finding purpose later in life — giving the new drama a warmer emotional core beneath its increasingly strange collection of crimes.

For fans of character-driven mysteries such as Midsomer Murders and Grantchester, it sounds like one to watch.

An unexpected return brings two detectives together

The first mystery begins when DI Glyn Walsh unexpectedly cuts short his bereavement leave.

Returning to work places him alongside DS Sion Dearden, and the pair are immediately confronted with a complicated murder.

An esteemed university professor has been killed.

Finding the culprit takes the detectives inside the darker corners of the local university, where the respectable academic environment conceals considerably more than it initially appears.

Glyn and Sion must work their way through the institution and the people surrounding the victim to uncover who had reason to kill the professor.

Solving that murder, however, provides little opportunity to recover.

More bodies are coming.

A poisoned head teacher and a bizarre drowning

Among the cases awaiting the pair is the apparently inexplicable death of a local head teacher.

The victim is poisoned — but then somehow drowns while wild swimming.

That combination leaves Glyn and Sion facing exactly the sort of puzzle around which cosy crime dramas thrive.

The death appears strange enough before investigators even begin asking who wanted the head teacher dead and how the circumstances surrounding the drowning fit together.

Then another case takes the detectives into completely different territory.

A triathlon becomes the setting for a mysterious case of mistaken identity.

The BBC has deliberately kept the full circumstances surrounding the murders under wraps, but the early descriptions suggest that each episode will provide the detectives with an unusual puzzle rather than straightforward police procedural work.

Solving murders is only half their problem

Glyn and Sion’s partnership extends beyond the police station.

The two men also find themselves living under the same roof.

That arrangement gives Old Town Murders another source of comedy and character drama between investigations.

Instead of detectives simply meeting at crime scenes and separating at the end of the working day, the pair cannot easily escape one another.

Their professional partnership spills into their personal lives.

It is here that the show’s wider themes become particularly important.

Both men have reached a point when their lives are changing, and their unexpected friendship offers an opportunity to discover what comes next.

The murders provide the mysteries.

Their relationship provides the heart.

Mark Lewis Jones leads as DI Glyn Walsh

Welsh actor Mark Lewis Jones takes the role of Glyn.

Viewers may recognize him from an extensive television career that includes The Crown, Baby Reindeer, Out There and Men Up.

Glyn’s early return from bereavement leave immediately suggests that the detective will be carrying more than professional responsibility into the opening investigation.

His grief forms part of the character’s attempt to rebuild his life.

Rather than presenting him simply as another brilliant detective with an eccentric investigative technique, Old Town Murders appears interested in what happens when someone tries to rediscover purpose after loss.

That emotional starting point explains why his developing friendship with Sion is so central to the series.

Steffan Rhodri completes the unlikely partnership

Steffan Rhodri plays DS Sion Dearden.

Rhodri is particularly recognizable to British audiences as Dave Coaches from Gavin & Stacey, while his dramatic work includes Steeltown Murders and Men Up.

The latter is particularly significant.

Rhodri and Lewis Jones previously appeared together in the BBC drama, and that collaboration ultimately helped inspire Old Town Murders.

Creator Matthew Barry also worked on Men Up and has revealed that he specifically wrote his new detective series for the two actors.

That existing familiarity could prove important to the chemistry between Glyn and Sion.

Cosy crime dramas often depend as much on the relationship between their investigators as the murders themselves.

Here, that relationship was built into the project from its earliest stages.

The supporting cast contains plenty of familiar faces

The two leads are surrounded by a strong British ensemble.

Bethan Mary-James, whose credits include The Guest and Death Valley, plays DC Remy Jones.

Catherine Ayers, seen in The Guest and Missing You, appears as Chief Superintendent Melanie Morris.

Julie Graham joins them as forensic biologist Pamela Thomas.

Graham will be particularly familiar to crime-drama audiences from projects including Shetland, while her recent credits include This City Is Ours and Time.

James Bamford, whose previous work includes The Red King and Masters of the Air, rounds out the investigative team as DC Neil Miller.

That ensemble gives the series room to build a broader police world around its central duo rather than leaving every element of the investigation to Glyn and Sion.

From the writer behind The Guest and Men Up

Matthew Barry created and writes the series.

His previous credits include BBC drama Men Up and psychological thriller The Guest.

For Barry, however, Old Town Murders is intended to operate as something more than another murder-of-the-week drama.

“Old Town Murders is more than a crime drama; at its heart, it’s about friendship, reinvention and the courage to begin again later in life,” he said when the series was announced.

Barry also confirmed that the two central roles were conceived specifically with Lewis Jones and Rhodri in mind following their previous collaboration.

That emphasis on later-life reinvention could help distinguish the show from the increasingly crowded field of British cosy mysteries.

The detectives are solving other people’s mysteries while attempting to work out what they want from their own lives.

The team behind Fool Me Once is producing

There is another familiar name behind the cameras.

The six-part series is being made by Quay Street Productions, the company behind dramas including Netflix’s Fool Me Once and ITV’s After the Flood.

For BBC Cymru Wales, the combination of the production team, Welsh talent and distinctive setting is a significant part of the show’s identity.

Nick Andrews, Head of Commissioning for BBC Cymru Wales, described the concept as the point where “picture-perfect Wales meets murder mystery.”

He also promised a “thrilling, twisty tale.”

That description neatly captures the contrast the series appears designed around.

Beautiful coastal scenery on one side.

Dead bodies on the other.

Tenby could become one of the show’s biggest characters

The setting may ultimately prove almost as important as the detectives.

Old Town Murders unfolds around modern-day Tenby, the historic seaside town on the Pembrokeshire coast.

With its beaches, harbour, colorful buildings and coastal landscape, Tenby provides exactly the kind of visually inviting location that can make a cosy mystery feel distinctive.

The production is also filming in Cardiff and elsewhere along the South Wales coastline.

That gives the series an opportunity to contrast increasingly peculiar crimes with some of Wales’ most attractive scenery.

It is a combination British television has used effectively before.

Midsomer Murders turned picturesque English villages into an improbably lethal collection of communities, while Shetland made its remote Scottish landscape inseparable from the mysteries unfolding within it.

Old Town Murders could do something similar for the Welsh coast.

Cosy crime continues to thrive

The timing is particularly interesting given the continuing appetite for gentler, character-led murder mysteries.

Shows such as Midsomer Murders and Grantchester have demonstrated remarkable longevity, while newer dramas continue experimenting with the familiar formula of distinctive investigators, picturesque locations and puzzling deaths.

The attraction is not necessarily graphic violence or relentlessly grim storytelling.

Instead, viewers are given a mystery they can attempt to solve alongside characters they enjoy spending time with.

Old Town Murders appears to understand that formula.

Its crimes sound complicated enough to provide genuine mystery, but the friendship between Glyn and Sion is being positioned as equally important.

Six episodes, several very strange deaths

The BBC has already revealed enough of the cases to suggest considerable variety across the six episodes.

A respected university professor’s murder sends the detectives into the hidden world of academia.

A poisoned head teacher somehow ends up drowning during a wild swim.

A triathlon produces a perplexing mistaken-identity case.

And more murders will follow across the area.

Each investigation offers Glyn and Sion another puzzle while their unusual domestic arrangement and friendship continue developing in the background.

That structure could make the series particularly easy to binge.

Individual mysteries can provide their own payoff while the characters’ personal stories continue across the full six episodes.

Murder, friendship and starting again

Perhaps the most intriguing element is that Old Town Murders is not presenting Glyn and Sion as young detectives with their careers and lives still ahead of them.

The series is explicitly interested in beginning again later in life.

Glyn’s bereavement has disrupted the future he expected.

His return to work unexpectedly brings him closer to Sion, and solving murders together begins giving both men something beyond another case file.

That creates an unusually optimistic idea beneath a show filled with dead bodies.

People can lose direction.

Circumstances can change.

And sometimes a completely unexpected friendship can provide a reason to begin again.

The murders simply happen to be part of the process.

A promising new Welsh mystery is taking shape

There is still plenty the BBC has not revealed, including exactly how Glyn and Sion end up sharing a home and what personal complications will develop alongside the investigations.

But the ingredients are already promising.

Two established Welsh actors with existing chemistry.

A creator who wrote the roles specifically for them.

A strong supporting cast.

Six puzzling murder cases.

And one of Britain’s most picturesque coastal towns providing the backdrop.

For viewers missing the combination of eccentric cases, memorable detectives and beautiful scenery found in series such as Midsomer Murders and Grantchester, Old Town Murders could become a very comfortable new addition to the genre.

Filming is underway in Wales, with a release date yet to be announced.