Nicola Walker may be best known for her role in Unforgotten, but there’s another crime drama featuring the acclaimed actress that deserves a place on your watchlist. River, the six-part BBC series that first aired in 2015, combines a murder investigation with a haunting psychological mystery, creating a story that is difficult to stop watching once you get started.

Now available to stream on ITVX, the series stars Stellan Skarsgård as Detective Inspector John River, a gifted but troubled investigator whose life takes a devastating turn following the murder of his colleague and close friend, Detective Sergeant Jackie “Stevie” Stevenson, played by Walker.

The twist is that Stevie continues to appear to River, even after her death. As he struggles to understand what has happened to his partner, he finds himself confronted by other ghostly figures, too. The visions complicate his already difficult investigations, blurring the line between reality and his troubled perception of the world.

With a murder mystery at its heart and a deeply personal story unfolding alongside it, River offers a compelling alternative for anyone who enjoys thoughtful, character-driven crime dramas. If you’re ready to discover the series, here’s what to know about its story, cast, critical reception and where to watch it.

What is River about?

Written by Abi Morgan, the acclaimed screenwriter behind The Split, River is a six-part British detective drama that takes a distinctive approach to the familiar police procedural.

At its centre is DI John River, played by Stellan Skarsgård. He is an exceptionally talented detective, but he is also isolated and haunted by the people who have died in the cases he investigates. These apparitions follow him through his daily life, leaving him to navigate a world in which the boundaries between the living and the dead are far from clear.

The most significant presence is DS Jackie “Stevie” Stevenson, portrayed by Nicola Walker. Recently murdered, Stevie was River’s partner, colleague and close friend. Although she is gone, he continues to see and speak to her as he tries to uncover the truth behind her death.

As the investigation progresses, Stevie becomes more than a familiar face in River’s mind. Her appearances offer him insights into the case, while revelations about her life force him to reconsider how well he really knew the woman he trusted.

Meanwhile, River must continue working on other investigations, each bringing its own unsettling encounters with the dead. Balancing these cases with his increasingly fragile grip on reality becomes an additional challenge, raising questions about his ability to distinguish what he sees from what is actually happening.

The official synopsis captures the central mystery: “As the investigation into Stevie’s murder begins to reveal her deepest secrets, River has to question everything he thought he knew about his one true friend. Their relationship might have survived her death but can it survive the truth of who she really was in life?”

That question gives the series much of its emotional weight. Alongside the mystery surrounding Stevie’s murder, River explores friendship, grief, trust and the complicated truths that can emerge when someone is no longer alive to explain themselves.

Who stars in River?

Alongside Skarsgård and Walker, the series features an accomplished ensemble cast, with several familiar faces bringing depth to the people surrounding River and Stevie.

Here is the full cast list:

• Stellan Skarsgård as DI John River
• Nicola Walker as DS Jackie “Stevie” Stevenson
• Adeel Akhtar as DS Ira King
• Lesley Manville as DCI Chrissie Read
• Georgina Rich as Rosa Fallows
• Eddie Marsan as Thomas Neill Cream
• Turlough Convery as Frankie Stevenson
• Sorcha Cusack as Bridie Stevenson
• Steve Nicolson as Jimmy Stevenson
• Owen Teale as PSupt Marcus McDonald
• Michael Maloney as Tom Read
• Jim Norton as Michael Bennigan
• Peter Bankolé as Haider Jamal Abdi
• Adjoa Andoh as Sunday Akentola
• Shannon Tarbet as Erin Fielding
• Josef Altin as Christopher Riley
• Anamaria Marinca as Ema
• Andrei Zayats as Ukrainian Lad
• Lydia Leonard as Marianne King
• Pippa Bennett-Warner as Tia Edwards
• Franz Drameh as Bruno
• Stefan Kalipha as Omari Tadros

Skarsgård anchors the drama as a detective wrestling with his own inner turmoil, while Walker brings Stevie to life through a character who remains central to the story even after her death. Their unusual partnership is a key part of what sets River apart from more conventional crime series.

Is there a trailer for River?

Yes. If the premise has caught your attention, the trailer offers a glimpse of the series’ unsettling atmosphere, its murder investigation and the complicated relationship between River and Stevie.

You can watch the trailer for River (2015) on YouTube:

Is River worth watching?

If you enjoy crime dramas that dig beneath the surface of a murder investigation, River is well worth considering.

The series combines the familiar elements of a police procedural with the eerie atmosphere of a ghost story. Rather than relying solely on clues, suspects and dramatic revelations, it also invites viewers into the mind of a detective whose unusual experiences shape the way he approaches his work.

The result is a drama that can be unsettling, tender and unexpectedly witty. Its investigations explore not only the circumstances surrounding individual crimes but also the people involved and the reasons that can lead someone to commit murder.

Skarsgård’s performance has been a particular highlight for critics, who have praised the complexity he brings to River. The character’s intelligence is matched by his vulnerability, making his struggle to separate his professional responsibilities from his personal experiences an essential part of the story.

Walker is equally important to the series. Although Stevie’s death drives the central mystery, her continued presence gives the drama an emotional dimension that extends beyond the question of who killed her. As River learns more about his friend, he must confront the possibility that their relationship was not quite what he believed.

Critical reception has also been strong. River received a 100% critics’ score on Rotten Tomatoes, based on 16 reviews listed for the series. Reviews have highlighted its unusual approach to detective fiction, the writing by Abi Morgan and the performances of its leading actors. The Guardian also included the drama in its Best TV of 2015 coverage.

For viewers looking for a crime series with psychological depth, emotional complexity and a distinctive supernatural element, River offers a rewarding alternative to a standard murder mystery.

Where can you watch River?

The good news for UK viewers is that all six episodes of River are available to stream on ITVX.

The platform’s official listing describes the drama as a story about a detective haunted by the ghosts of murder victims and struggling to maintain the boundary between reality and madness.

With the full series available, you can follow River’s investigation into Stevie’s death from beginning to end and watch the mystery unfold at your own pace.

What else can you watch Nicola Walker in?

If River leaves you wanting more of Nicola Walker, there are two other dramas worth adding to your viewing list: Unforgotten and The Split.

Unforgotten

Walker is widely recognised for playing DCI Cassie Stuart in ITV’s acclaimed crime drama Unforgotten. She appeared in the first four series alongside Sanjeev Bhaskar, whose character, DI Sunny Khan, works with Cassie to investigate historical crimes and uncover long-buried secrets.

The series is a natural choice for anyone who enjoys carefully constructed mysteries, complex characters and investigations that reveal more than initially meets the eye.

You can stream episodes of Unforgotten on ITVX.

The Split

For something different, Walker also stars in The Split, a drama centred on the Defoes, a family of divorce lawyers forced to confront their own complicated past.

While River explores grief, murder and the fragile boundary between reality and the supernatural, The Split turns its attention to family relationships, personal history and the challenges that come with navigating life and love.

All three series of The Split are available to stream on BBC iPlayer.

For fans of Nicola Walker, River is another compelling showcase for her talent. With a gripping central mystery, a memorable lead performance from Stellan Skarsgård and a story that combines crime-solving with deeply human questions, this six-part drama is an excellent choice for your next television binge.