Towards the end of the Vigil season 2 finale, it became clear that the killings were committed as part of a wide-ranging conspiracy, with Eliza Russell most directly culpable, having piloted the RPAS that shot her fellow members of the military.

She had committed the murders on the instruction of air vice-marshal Marcus Grainger and Derek McCabe.

At the start of the episode, Russell shot and killed Wes Harper, and made it look like self defence. She was placed under armed guard, but later went missing.

Meanwhile, Kirsten saw Ross Sutherland meet McCabe at a discreet rendezvous, where McCabe killed Sutherland and then injured Kirsten, landing her in the hospital.

Amy landed back in Scotland and took over the investigation on home turf. Russell and McCabe were both hunted by the police.

Amy found Russell being held by Ramsay in a secure location, and she finally confessed to Amy that she manipulated Sabiha into stealing the RPAS console, that she had Chapman killed because he was looking into the missing console, that she killed Wes Harper because he was blackmailing her, and that she hired Ross Sutherland.

She admitted that Dundair was a false flag to build a case for escalation and for the UK to formally enter the war in Wudyan against Jabat Al-Huria. The reason so many people had to be killed was that it had to look real, and not like an accident.

Russell said that she did it for money that McCabe was paying her – his stock prices rose dramatically as the UK looked set to enter the war in Wudyan.

While off the record, Russell revealed that she was actually made to commit the murders by the security services. Ramsay assured Amy that they weren’t involved, and certainly that he wasn’t.

Meanwhile, Amy realised that Russell didn’t really hire Sutherland – he was hired by Grainger, secretly a friend of Sutherland’s, who she is covering for.

Ramsay helped Silva uncover the evidence needed to send Grainger down, confirming that Sabiha knew about her father’s trip to Wudyan before he did – she could only have known that if she found out, down the chain, from Grainger.

Grainger realised he’d been found out and confessed, saying he made the decision to kill his own troops for the greater good.

His and Russell’s trial was held in a closed court, when journalist Firas Zaman was permitted to make a statement.

They were both convicted of high treason. Russell was given a minimum term of 30 years, while Grainger was given a life sentence, with a minimum term of 45 years, meaning he was likely to die in prison.

What happened to Amy and Kirsten?

BBC / World Productions LTD / Nicky Hamilton

Kirsten left hospital fully recovered and with her baby still fine and healthy. She, Amy and Poppy headed home, happy and awaiting the next chapter of their lives.

Amy was later seen attending the trial of Russell and Grainger, before leaving and telling Kirsten on the phone that she was coming home.