This week’s episode of Orphan Black is heavily concerned with the past. Sarah’s past comes back to haunt her in the form of Helena, after she’s spent her time digging up the history of Mrs S and the secrets of Project Leda.

We open on the revelation that it was Cal who smashed into the car and that he appears to have killed Daniel in the process. He assures Sarah that Kira is safe before they hide the car and flee the scene.

We soon learn that Alison is now in rehab, which makes complete sense considering her recent reliance on alcohol. As Alison’s recovery begins, Helena’s comes to its end. Grace attempts to murder her, although we all know Helena isn’t so easily got rid of. She leaves the Proletheans, rightly not trusting them at all. Having Helena out in the wild is also the best way for Orphan Black to keep things unpredictable.

The instability of Kira’s situation is something you’d expect the show to want to solve quickly by putting her with Cal for a more permanent basis so that it can focus on the action elsewhere. It may still do that but it looks like we’ll keep checking in with her and I think the show’s better for it. Getting to know Kira well is important, and the scenes she shares with Cal are emotional and interesting. In some ways it doesn’t matter if he is or is not her real father, he demonstrates that he’s got the right qualities to be her dad.

Alison’s situation is looking bleak, even if we can agree that rehab will be good for her it is still sad to see her put in such an undignified situation and then told by Donnie that he’ll take her kids from her if she’s unable to complete the program. By moving Alison into a new location, though, she’s going to have the best opportunity yet to escape having to live with the man she now knows to be her monitor. It also looks like Felix is back to helping her out in earnest, offering the kind of support she’s going to need to get better.

The most obvious way that ‘Governed as It Were by Chance’ focuses on the past is in its revelations about Project Leda. Mrs S reunites with an old flame and the man who originally brought Sarah to her, Carlton (Roger R Cross) and we get to see more of the unpredictable side of her that has been on display this season. While she’s mostly here to offer up warnings about the can of worms that Sarah might be about to open, there’s something compelling about her arc.

Helena’s escape from the Proletheans is important because it brings with it the answer to exactly what they were doing with her in the first place. It turns out that, unsurprisingly, they’re interested in finding out whether she can reproduce and have taken one of her eggs for artificial insemination. This isn’t something we’re told until the end of the episode, but Helena’s flashbacks to a violent experience in their lab tells her side of the story and makes it clear she’s justifiably both angry and scared.

Eager to stay one step ahead of Rachel, Sarah infiltrates her apartment after discovering that the “pro-clone” was raised by the pair behind Project Leda, Susan and Ian Duncan. She’s soon found by the obviously not-dead Daniel, and he strings her up to torture her and find out what she knows.

Orphan Black gets really dark in this scene, as Daniel takes a razor blade to Sarah’s skin before Helena appears to finish off Rachel’s henchman/monitor/boyfriend. It’s a violent, bloody and confused family reunion that concludes this episode, but it’s ultimately surprisingly touching to see poor, damaged Helena tell Sarah she needs her help even if she doesn’t fully understand why.

Aired at 10pm on Wednesday 21 May 2014 on BBC Three.