Betrayal ending explained: What was going on with Mehreen?

*Warning - contains full spoilers for all four episodes of Betrayal.*

All four episodes of new spy thriller Betrayal are now available to watch on ITVX, with the series following John (Shaun Evans), an MI5 operative who finds himself under investigation after acting on intel he failed to report, in a meeting that saw a man get killed.

John subsequently becomes convinced that an attack on British soil is set to be perpetrated, led by a hardline faction in the Iranian regime. Meanwhile, he tries to keep his crumbling marriage to Claire (Romola Garai) together.

Throughout the series there's also the question of Mehreen (Zahra Ahmadi), the MI6 agent brought in to take over John's duties while he is under internal investigation. Following a major twist at the end of the second episode, John, and we the viewers, start to question just where her loyalties lie.

But what is revealed about Mehreen and how does the series all come to an end for John, his MI5 team and his wife Claire?

Read on for everything you need to know about the ending of Betrayal on ITV.

Betrayal ending explained: What was going on with Mehreen?

Despite it at one point seeming as though Mehreen was betraying her country, working with the Iranian regime, she was actually still working for MI6, in a scheme unaware to MI5.

She had been working with General Qasem Asadi, who was an informant. The plan was for him to look like he was going ahead with a nerve agent attack on an event, but at the crucial moment, the device was intended not to work.

John believed the event was a speech at a university being made by Iranian dissident Fatemah Feyzi, but that turned out not to be the case. He was still convinced that the attack was going ahead, just on a different target.

After Asadi hinted that his family were in trouble, Mehreen found out they hadn't been seen in Iran for five days - Asadi had been compromised.

Asadi took John's wife, Claire, and babysitter, Marta, hostage and called him, telling him to come alone. As they were all held together at gunpoint, Mehreen came to the rescue.

She blew Asadi's cover, at which point he killed Hossein, another member of the Iranian regime behind the plot, who didn't know about his MI6 allegiances.

Asadi then held Claire at gunpoint, and revealed that the attack was to take place at an event celebrating the Iranian New Year (Nowruz) in Stockport, at the South Manchester Persian Centre.

Once they had the information they needed, Mehreen shot Asadi in the head, killing him instantly and saving Claire.

Did John foil the plot?

Yes — he did foil the plot. John and his team called in the threat to the wider MI5 institution and the police, and an armed response unit was sent in to stop Craig Beeston, Karlson Griffiths and the rest of the team.

The armed response team evacuated the building, took out the assailants and found that the nerve agent device was active. A hazmat team arrived and sealed the device.

Simone later revealed that the Prime Minister was informed and the President of Iran was spoken to. He was said to be moving against the hardliners in the regime, and planned the plot by the end of that day.

She also revealed that Asadi's family had left Tehran and were on their way to the UK via Germany.

Given his work on the job, Simone said that John would be staying at state threats - although he would have to do refresher courses on protocol and the organisation's expectations of him.

Mehreen revealed that she would also be staying in the department. Given what happened with Asadi, MI6 refused to take her back. She also hinted that she killed Asadi not just to save Claire, but also because his survival would threaten the reputation of the security services.

What happened between John and Claire?

Earlier in the season, it looked like John and Claire were separated for good. His refusal to put his family before his work at any time, the history of his affair and her recent affair with Martin appeared to leave things irreconcilable. John also almost slept with Mehreen, but decided against it at the last moment.

However, as the season came to an end John finally let Claire in, telling her that he and the team had managed to stop the attack. He also revealed that her affair with Martin had made him realise how he'd been making her feel for years.

Claire said she didn't know what was going to happen between them, but that she felt she understood him now in a way she never had before.

At the very end of the season, John and Claire were seen back in couple's therapy, being asked how things had been and what they'd been up to. They looked at one another, unsure how to answer.

Betrayal is available to stream in full on ITVX.

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