‘The monster was only pretending to be asleep’ reads the caption on a scary painting composed by one of Joanna’s school children. It’s a variation on the famous line in The Hobbit, in which Bilbo Baggins sneaks into the mines of the Lonely Mountain and finds Smaug the Dragon there waiting for him. Such flights of fantasy don’t belong in The Cry, but the monsters still exist. (some spoilers ahead)

In this final episode, Joanna (Jenna Coleman) begins to fix the pieces together. After the revelation from last week, where we found out that she’s being accused of the murder of Alistair (Ewen Leslie), we follow the events leading up to that point. The police have put the investigation on hold, and Joanna and Alistair are adjusting to their new life, post-Noah, in Scotland.

This episode doesn’t dish out the stomach-churning emotions of episode three, nor is the situation as intense after the investigation has essentially been called off. But writer Jacquelin Perske and director Glendyn Ivin provide a finale weighted with absorbing guilt and lies.

Alistair, solely concerned with his own motivations, signs up to a book deal discussing their story, which is very unlikely to be a truthful account. He doesn’t even consult Joanna, and it gets to her – she wants it all to disappear, but it refuses to. As the hard-nosed detective says at the start of the episode: ‘People think the weight of guilt will lessen with time. But in my experience, it’s quite the opposite’.

Jenna Coleman the cry
Joanna (Jenna Coleman) wakes up in the hospital

But Joanna and Alistair do have to live with what they’ve done even if, like Joanna, they didn’t know they were doing it. She struggles to endure Alistair – his schemes behind her back, his subtle deceptions – and tries her best to live with him, keeping him happy at all costs. The fragments of disturbing memories even begin to soften. But, as Joanna realises, this has even more horrific implications. Alistair begins to soak into Joanna, with such quiet build-up in Perske’s writing, existing inside her like a permanent spectral presence.

This series has been one of the most emotionally hard the BBC has produced, even within their recent television renaissance. Coleman in particular exudes such heart-ripping grief that one scene – in which she lays her head on a patch of grass under a tree – is like a traumatised painting.

The finale is muted compared to the devastation rippling through the other episodes, and contains an element of winding down – but it reaches an excellently unsettling conclusion. Its closing revelation is predictable, but not annoyingly so, and Ivin directs it with stirring suspense. If one thing is to be taken from The Cry, it’s that monsters don't leave even when they’re dead. Nor do the innocent.