The Hour star confirmed to join Until I Kill You actor in new ITV drama Betrayal

Garai is best known for her recent roles in BBC's Vigil season 2, Netflix's Scoop and Just Act Normal, as well as previous starring roles in various TV series like The Hour, The Following Events Are Based on a Pack of Lies and Becoming Elizabeth.

Of course, Evans is best known for his starring and long-held role in ITV's Endeavour, having also starred in Vigil and more recently in Until I Kill You alongside Anna Maxwell Martin.

Evans will be leading the cast of Betrayal as MI5 agent John Hughes, while Garai will star as John’s partner Claire, "whose trust in him is strained by the secrecy and demands of his work," according to the synopsis.

We know that the the series is set to explore the strain modern intelligence work places on those working in MI5 operatives, with John's own life being rocked by betrayal.

As per the official synopsis: "Betrayal follows John Hughes, a mid-career MI5 officer grappling with a rapidly changing security landscape and his own personal demons. When John’s clandestine encounter with a potential British-Iranian informant ends in bloodshed, he comes under scrutiny from superiors including Simone Grant.

"As John navigates the murky world of espionage, the strain on his marriage to GP Claire becomes increasingly unsustainable.

"Tensions escalate further with the arrival of Mehreen Askari-Evans, a sharp, ambitious operative who has recently transferred from MI6, challenging both his professional standing and emotional control."

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As well as Evans and Garai, the rest of the cast includes Beyond Paradise's Zahra Ahmadi as recent MI6 transfer Mehreen and Nikki Amuka-Bird (I, Jack Wright) as one of John's superiors Simone.

The rest of the Betrayal cast includes Gamba Cole (The Outlaws), Omid Djalili (The Letter for the King), Matthew Tennyson (A Midsummer Night’s Dream), Hayley Tamaddon (Unforgotten), Anthony Flanagan (Protection), Paddy Rowan (G’wed), Waj Ali (Out There) and Karim Kadjar (Wolf Hall).

Emma Cunniffe (Suspect: The Shooting of Jean Charles de Menezes), Georgina Rylance (Benediction), Ben Lambert (Outlander), Julia Watson (Doctor Who) and Julian Wadham (Black Doves) also join the cast alongside TV newcomers Elham Karimpour, Aidan Rivers, Corin Silva and Eliza Agrosoaie.

While the series doesn't yet have a confirmed release date, we do know that Betrayal is set to land on our screens sometime in 2026. Filming for the series has now kicked off in Manchester and Liverpool, with BAFTA-nominated Julian Jarrold (A Very Royal Scandal) in the director's chair and Irma Inniss (Mr Loverman) taking up the mantle as producer.

Betrayal will premiere on ITV1 and ITVX in 2026.

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