Desperate times call for desperate measures, and this has never been more true than in the final episodes of "Orphan Black's" fourth season. With their backs against the wall, Sarah and Cosima will do the seemingly unthinkable — allying themselves with their enemies.

Things haven't been going so well for the sestras recently, with Sarah and Cosima struggling to come to terms with their losses, while Allison is threatened by Detective Duko (Gord Rand) and forced to reveal her sisters' location.

But it seems the clones are fighting back as episode 9 will find Sarah (Tatiana Maslany) and Rachel working together in a bid to take down a mutual enemy — Evie Cho (Jessalyn Wanlim) and the new HBIC. Cosima and Susan Duncan (Rosemary Dunsmore) are also teaming up to find a cure for the Leda and Castor clones. But Cosima's plan has her butting heads with Susan over its moral implications. Meanwhile, Adele (Lauren Hammersley) looks into Donnie's (Kristian Bruun) case and realizes that Felix (Jordan Gavaris) might be keeping some dangerous secrets. Helena's return is not helping matters, as far as Felix is concerned, as he's forced to make a difficult decision.

There are only two episodes left before the series wraps up its fourth season and things are rapidly moving forward. A trailer for the upcoming penultimate episode, "The Mitigation of Competition," unfolds with a surprising sight — Felix greeting Rachel. Sarah is with him and says that "this is a bad idea." There are also shots of the police checking out a crime scene and Sarah being asked by her partner to stay in the car.

Cosima is shown looking into at a microscope as she continues her search for a cure. Meanwhile, it seems that Rachel and Sarah will really be working together. Helena is then seen arriving, much to Felix's surprise. Another Castor clone calls someone and warns them that "there's a complication," and whether this is about Helena's arrival remains to be seen. The clip ends with Allison going down the stairs and is shocked at what she finds. A man is shown tied up, while an unknown person says that they "will have a little chat."

The series is certainly moving quickly toward its endgame, as "Orphan Black" will reportedly wrap up the clones' journey next season. The show's co-creator, John Fawcett, previously admitted to E! Online that the sestras' story has already been mapped out.

"We will arrive at some kind of end destination by the end of season five," Fawcett said.

In light of that information, fans should take the time to savor and enjoy the remaining episodes.

Viewers can catch episode 9 of "Orphan Black" season 4 on BBC America on June 9 at 10 p.m.