It’s a politically charged outing this week as the Lyell team investigate the murder of Amir Aziz, a Muslim man with a strong connection to the community.

Before the main thread of the story begins we’re taken to Bosnia, in 1995, where a young Sarah Begovic witnesses the murder of her father. It’s a harrowing opening which takes its inspiration from the real life Bosnian massacre.

Back in the present, an adult Sarah arrives in London with a baby in tow. It’s quickly established that Sarah has smuggled heroin into the country and she’s later suspected of being involved in terrorist activities. There’s a lot of social commentary in this episode which centres around current UK attitudes towards terrorism, race, Muslims and refugees coming into the country.

Graham Mitchell’s script is particularly upfront with dialogue such as, ‘he’s called Muhammad, he must be about to detonate,’ summing up how deeply the issue of race runs under current society. It relentlessly underpins this tale and, in the 1995 Bosnian massacre, shows a causal link between past events and the problems of the present. The knock on effect of these events, including the Iraq war, shows the ease in which terrorist propaganda can spread and gain new believers.

Sarah’s mother is taken in for questioning and, inevitably, the discussion turns to the massacre she and her children escaped. DCI Michael Waite attempts to goad her, ‘you never wanted revenge for that?’ to which Alma Begovic replies, ‘what would taking revenge achieve?’ It’s a powerful scene that shows the divide between mother and daughter and how this one terrible event set them both on different paths.

Elsewhere it seems as if a happy romance may be blossoming between Thomas and, this week’s DI, Nina Ryman. There’s an immediate spark between them and they’re later shown to be getting to know one another and it comes of no surprise when they end up in bed together. However, there’s a shocking end to the first part when Nina is shot.

It heats up in the second part of ‘Flight’ as Thomas arrives on the scene. ‘Is she alive?’ He asks, very obviously shattered by the sudden turn of events. ‘Just,’ is Nikki’s reply and a shadow of doubt hangs over Nina’s chances of survival. It’s a cruel twist for Thomas who might just have found someone at last.

Sarah’s on the run with Zak Latif and their baby as they hastily return to their hideout and the plans for their jihadism step up a gear. Sarah tells Zak that she got the money to come back through drug trafficking. ‘Maybe that’s how they found me?’ Sarah asks with a hint of desperation in her voice.

This is very much Sarah’s story and the script drums up a lot of sympathy for her situation as she’s consistently torn between her ideals and her unequivocal love for her child. Her doubts become much more pronounced across the duration of the episode and the question of whether she has it in her is asked.

The stakes are increased when the police and pathologists realise a terrorist cell is active in London, and Waite raises the threat level to substantial. It’s a matter of time before Zak and Sarah carry out their attack but there’s still no indication of their target.

As they continue their investigation, they question whether Aziz knew something about the suspects’ plans and if that was why he was stabbed. Here, Mitchell inserts more commentary on the present climate as Nikki asks, ‘he was Muslim, they attack Muslims now?’

There’s a shock twist in the tale when Kamal Rashid meets up with Sarah and Zak and begs them to reconsider their path. With their refusal, Kamal informs them that he has no option but to turn them in. Zak follows Kamal to a payphone where, after Kamal doesn’t relent, he stabs him. It’s here that Zak makes his first mistake as he’s briefly struck by emotion and drops the knife beside Kamal’s body. Zak takes the baby and we see him say a heartfelt goodbye to his son as he abandons the pram outside a hospital.

At the Lyell centre, Thomas is able to match up the knife with the broken end found in Aziz’s body and, in doing so explicitly connects Zak to both murders. There’s a further twist in store when Clarissa discovers Kamal was Zak’s father, and brick dust found on the knife suggests the location of the hideout.

Sarah’s conflicted priorities come to a head when she decides to choose her son over her planned jihad. ‘I want to be with my son,’ Sarah informs Zak who’s less than thrilled by her defection. Our sympathies for Sarah are significantly played upon here as she’s forced into carrying out the plan on the threat of her son being harmed if she doesn’t comply. Her situation has become utterly desperate and we see how strong her love is for her child.

By the time the police storm the location, in scenes juxtaposed with Zak recording his video message, the hideout has already been abandoned but examination of photos on their laptop reveal the target, Park West Conference Centre.

At the Conference Centre, women are seen running, screaming out of the building. They hear a gunshot and their sights become fixed upon Zak who’s swiftly taken out. It’s revealed that a conference on women in Islam was being held by an ex-Cabinet minister, Sabeen Malik, whose known for speaking out against jihadism.

With Sarah missing they realise Malik is the intended target and the story reaches a tense climax as Waite attempts to talk Sarah down. The way Waite uses Sarah’s son to get to her is quite uncomfortable and he’s painted in an unfavourable light when he orders her to be taken out even after she lowers her gun.

Silent Witness shows itself unafraid to tackle the difficult questions of modern society and raises its own questions over the long-term impact of past events whilst still weaving these strands into a highly compelling tale.

Aired at 9pm on Monday 11 January 2016 and at 9pm on Tuesday 12 January 2016 on BBC One.

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