The discovery of the circumstances of Beth’s suicide is a huge deal and completely changes the way the police have to approach this investigation. It’s a big moment played as a small moment, though, because the final few scenes pile on really stunning revelations that only the most astute viewers would have been able to predict.

The writers of Orphan Black manage to rather masterfully play with a wide mix of emotions in the scene where Sarah not only meets her birth mother but learns that Helena, who she currently has tied up in the back of her car, is her twin sister. It’s excellently done, probably one of the strongest moments of the season and another terrific chance for Tatiana Maslany to demonstrate her considerable acting talent.

Before we reach that point, though, we go through the trying ordeal of watching Kira’s surgery after the car accident. Everyone’s reactions in these scenes are moving and while it’s unsurprising that she survives, the doctor’s shock at her recovery suggests there’s more to explain and that some genetic ability may have been passed down to her.

‘Unconscious Selection’ also sees Cosima finally realise that she hasn’t been playing Delphine anywhere near as successfully as she thought. However, Delphine might have genuine feelings for her too and it’s all looking a bit messy. This material has been rather rushed and is unconvincing but thankfully it’s one of the smaller Orphan Black subplots.

More interestingly, Dr Leekie makes contact with Sarah and tries to establish a deal with her that involves the exchange of Helena for her freedom. Unsure of what she’ll choose, Sarah eventually frees Helena from Tomas but decides not to turn her over to Leekie when Mrs S urges her to reconsider.

Individual priorities resurface in the season finale, though, as ‘Endless Forms Most Beautiful’ puts all of the clones in difficult positions and forces them to make a choice about whether they can truly trust Leekie and his associates. We meet another clone, Rachel, who has been raised by the Neolutionists and is working for them to get Alison, Cosima and Sarah to sign a contract now that they are self-aware. Orphan Black wisely still keeps most of the conspiracy hidden, which means there are numerous possibilities for development in the second season.

Meanwhile, Art tracks down Vic and the whole cloning situation begins to unravel itself before his eyes. He sees Alison and immediately realises that she’s not Sarah posing as somebody else. Now that the police have learnt about Beth, Sarah and Alison, they’ve got to start pursuing wilder theories and it shouldn’t take long for the puzzle pieces to come together. Helena escapes from Sarah’s basement early in the finale, running away to figure out what to do with the information she’s just been told about her past.

Rarely one to take the expected course of action, Helena decides to kill her birth mother because she’s the one who separated her from Sarah and the reason she’s lived the way she has. In the ensuing confrontation, Sarah rather surprisingly shoots Helena. There’s a high chance she’ll survive, as she’s one of the most interesting clones and her story still has the potential to go in a very intriguing direction, but that doesn’t take anything away from how huge it is that Sarah was able to pull the trigger.

Alison decides to sign the contract, believing that it’ll keep her family safe and hoping that it’ll give her a new start after she helplessly stood by and watched Aynesley die in a seriously twisted way. That scene with Aynesley is one of the most shocking of the finale, it’s a really inventive death that is difficult to watch and indicative of just how much Alison has lost the control she craves.

Straight after her decision to sign the agreement, though, Cosima and Delphine work out that the clones are technically patented and that to sign anything could make them property of the The Dyad Institute. Sarah refuses to sign it but she may well have paid a steep price, returning to find the house ransacked, Mrs S and Kira nowhere to be seen.

This has been an outstanding debut season for Orphan Black. The final two episodes are full of bold and exciting storytelling choices that both tie up loose ends from the threads of this season and set things up for the second one. Maslany’s incredible acting is at its most impressive when many of the clones come together, and her remarkable talent is constantly on display here.

‘Endless Forms Most Beautiful’ constructs a simple and effective way to end the season that’ll have everybody desperate to see what happens next.

Aired at 9pm / 9.45pm on Friday 1 November 2013 on BBC Three.

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