Silent Witness episode 1 review: A gripping start as Nikki is haunted by ghosts from her past

Naturally, Nikki's past experience with Weston makes it rather difficult for her to view this new case in an objective manner, and she seems desperate to prove that he's the one responsible for the death in spite of any evidence to the contrary – especially given an appeal is underway which could get him released from prison early on some, shall we say, rather contentious grounds. It falls to Jack to keep Nikki in check a little, and in doing so we get the first glimpse at what the BBC has promised will be an increasingly close relationship between the pair this series.

There's a scene between them towards the beginning of the episode, in which Nikki admits to the fact she's feeling "a bit weird today anyway" since she's been asked to take over some of Thomas Chamberlain's lectures. "I miss them," she says, of both Thomas and Clarissa, and the absence of the two departed characters is clearly felt throughout – even if writer Lena Rae is careful not to overplay this too much. There is a rather melancholy feeling hanging over the Lyell at the moment though, and it adds another dimension to an already interesting case.

In addition to Tittensor, Connie Walker also returns as Scott's mum Pamela Weston – and she's found herself the victim of several taunts and threats regarding her son, despite her own insistence that he should remain locked away at all costs. Alas, by the end of the episode Pamela has met a horribly grisly fate, burned alive in her own house, adding yet another mystery to the central case. On the one hand, fingers seem to point towards Scott's girlfriend Paisley (played by Harry Potter star Evanna Lynch) after she paid a visit to Pamela earlier in the episode – but is there a chance she was actually warning her? She was certainly speaking with a great degree of urgency when she suggested that she had something to show her...

As to the central mystery of who killed Jay, it seems pretty likely that despite Nikki's fixations, someone other than Scott Weston was responsible. So who could it be? Well, we learned at the very end of the episode that despite earlier suggestions that Jay could have perished due to his injuries or hypothermia, the actual cause of death was an anaphylaxis shock – meaning that he had been exposed to something or another that he is severely allergic to. There are a couple of possible culprits: another of the prison's inmates, Lewis, is certainly an intimidating, unpleasant presence who was heard previously making death threats to Jay, but again this seems perhaps a little too obvious.

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So what about Leon? The prison kitchen worker admits to having been long term friends with Jay – having hidden the fact that he grew up on the same estate, and while it's unclear what motive he might have to kill him, there are two things that mean he can't quite escape suspicion at this stage. For one, given his previous ties to Jay, he seems more likely than anyone else in the prison to be aware of the deceased's allergies, while as a kitchen worker he presumably also has access to various allergens that might have caused the shock. Moreover, he was also the person responsible for hiding Jay in the fridge in the first place and so in all likelihood the last person to see him before he died. It still seems a long shot that Leon would have wanted to kill Jay, but it's too early to rule anything out yet.

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There's something fishy, too, about the prison governor Matt Blake (Kevin Doyle). When the prison workers are asked for voluntary DNA samples, Blake is particularly resistant, while he also seems keen to avoid questioning later in the episode – although he puts this down to his diabetes. That doesn't necessarily mean he had a hand in the death, of course, but it seems very possible that he's hiding something.

Anyway, going into the second part of the doubleheader tomorrow evening there is no shortage of talking points, theories, and character developments to discuss. And for fans of the show, it's just great to have Nikki and Jack back.

Silent Witness continues on BBC One on Tuesday 7th September at 9pm. Check out what else is on with our TV Guide, or visit our Drama hub for all the latest news and features.