The Nest’s final episode has certainly proven to be a divisive one. Some have praised the BBC One show’s ability to keep viewers guessing until the bitter end, while others have lambasted writers for piling too many plot twists into the hour-long finale.

Whichever camp you fall into, though, there’s no denying that it made for seriously gripping TV.

Picking up shortly after episode four ended – with Kaya (Mirren Mack), coming around to the idea of seeking custody over her daughter Gracie – we saw the Glaswegian teen growing ever closer to her mother, Siobhan (Shirley Henderson). And, as a result of this, she was soon persuaded to speak to a tabloid journalist about Dan (Martin Compston) and Emily (Sophie Rundle)’s surrogacy deal.

Naturally, the press has a field day, spinning countless headlines about the middle-class couple who attempted to buy a troubled young woman’s baby from her. They dig into Dan’s past. They expose shady business deals. They camp outside Dan and Emily’s home, desperately seeking comment. And they cast a dark shadow over the couple’s eligibility as adoptive parents for Gracie.

All of this, however, has an unwelcome side-effect for Kaya. Because, with her name and face plastered everywhere, she soon starts to see her own past dug up. Indeed, one angry individual presses dog excrement through the letterbox of Kaya’s “safe house” – which causes police to question her own suitability as a parent, too.

Kaya confronts Siobhan with this revelation, but her mother seems unperturbed. All that’s important, she tells Kaya, sounding more and more like the mum from Stephen King’s Carrie with every syllable, is that Dan and Emily don’t get Gracie.

Naturally, Kaya disagrees. She doesn’t want Gracie to end up in “the system” – she wants her to live a happy life, with a family who loves her. Siobhan sneeringly suggests that this would never be Kaya, because Kaya is a murderer.

And then, at long last, we find out the truth about that stabbing incident. In a flashback, we see 11-year-old Kaya watching on as her mother argues with her increasingly volatile (and pregnant) sister. When Siobhan grabs a knife, Kaya runs between the two women, grabs at the blade and… yeah. She accidentally stabs her aunt.

It took years of care and therapy for Kaya to realise that she wasn’t to blame for what happened. That she wasn’t the evil demon the tabloids painted her out to be. And she points out, fairly, that Siobhan never did anything to help her during that time: her mother didn’t explain the situation to the press, nor comfort her daughter in any way.

Why not? Well, because Siobhan still fully blames Kaya for what happened that night, it seems. And, as she lashes out at her daughter, viewers all around the nation tensed: could history be about to repeat itself?

As ever, though, The Nest defies expectations. Instead of another familial murder, writers have Kaya hurl cash at Siobhan. And her mother, clearly only back in her daughter’s life for one reason, painfully kneels to the floor, scrapes the £20 and £50 notes off the ground and then disappears, never to be seen again.

The twists, however, don’t end there.

For a while, it seems as if Kaya was going to win custody of Gracie. Indeed, police, medical and social care staff rule in support of her keeping the baby, in a particularly powerful scene.

“I think we know from experience that kids don’t really do clean slates,” insists the social worker assigned to Kaya’s case. “People’s stories are their stories. It’s incredibly important to children that they come from somewhere, and this baby came from Kaya.”

She adds powerfully: “I do believe, with support, she could provide a safe environment. And if we don’t give her that chance, are we not just repeating the mistakes of the past? Social engineering? Handing the babies of poor girls over to middle-class couples?”

Later, we learn that Emily and Dan have, similarly, come to the conclusion that Gracie should remain in Kaya’s care. So much so, in fact, that they promise to drop their own custody case and offer her both financial and practical support (whilst maintaining a healthy distance, of course).

Minutes before the episode ends, however, Kaya catches us all by surprise. Again.

“I want a life,” she explains to her social worker. “I want to do better than just having a kid for company… I want to be a businesswoman. I want to go on planes…

“I don’t know what the fuck I want, but I want things.”

Insisting that she didn’t need to sleep on her decision, Kaya determined that she did not want full custody of Gracie – but that, similarly, she didn’t want the bairn to go into care, either. And so, just like that, Emily and Dan’s luck changed: they were awarded temporary custody of the baby and fleeting sun-soaked shots showed them playing happily with the infant.

Kaya, meanwhile, was shown standing on the roof of a high-rise building, her hair and make-up absolutely immaculate, An unreadable expression on her face, she stared out into the city – and planned the future that she finally, finally had access to.

It was an interesting choice on behalf of The Nest’s writers: to somehow, against the odds, give viewers that rare happy ending. It’s worth noting, though, that they sought to teach us an important lesson in the process, too.

Firstly, there is no such thing as a ‘perfect’ parent. Everyone has baggage, everyone has issues, and there are always shades of grey. Secondly, there is, usually, only one right answer when it comes to a mother’s relationship with her child – and it all depends on her. Choice, as ever, is vital. It’s up to her if she’s ready, it’s up to her if she wants to give it a go, and it’s damn well up to her if she doesn’t, too. So long as it’s all done through the proper channels, of course.

And so, on that note, our watch over The Nest has ended. Roll on the next big BBC drama, eh?

Images: BBC One