“Orphan Black” doesn’t do small finales. Fans know that the end of the season is always explosive, and Season 4, episode 10, of the BBC America drama will be no different. In this finale, Sarah is going to try and put an end to Neolution.

It’s Cosima (Tatiana Maslany) who causes Sarah (Maslany) to make her move. “When communication with Cosima is cut off and Neolution appears to be within striking distance, Sarah’s alliance with Rachel [Maslany] goes out the window,” the synopsis reveals. Viewers knew that partnership wasn’t going to last, but why can’t Sarah talk to Cosima? If she is safe on the island, she should be able to chat.

The episode, titled “From Dancing Mice To Psychopaths,” will show Sarah taking down someone important.  “Sarah lures a high-level Neolutionist into a trap, and sets out to bring down Neolution once and for all,” the synopsis states. Photos reveal Mrs. S (Maria Doyle Kennedy) with Dr. Van Lier (Scott Wentworth), so it appears the Bright Born doctor is their target.

Orphan Black 410 Mrs. S (Maria Doyle Kennedy) is bringing Dr. Van Lier (Scott Wentworth) somewhere in the “Orphan Black” Season 4 finale. Photo: BBC America

Sarah might get some unexpected help from Krystal (Maslany). It looks like the clone is getting closer to figuring out who she really is. She even offers information about Delphine (Évelyne Brochu) to Felix (Jordan Gavaris) in exchange for the truth. “I am not giving you anything unless you tell me what’s really going on,” Krystal says in the trailer above. In photos from the episode below, Krystal is shown with Sarah in Felix’s apartment, so it seems like she’ll discover at least a few secrets.

Of course, fans really want to hear exactly what Krystal knows. Last week, Delphine was revealed to be alive, and she is the one sending Rachel messages through her fake eye. Though the French doctor is absent from the synopsis, trailer and photos, it seems pretty likely that viewers will see her in the finale.

The “Orphan Black” Season 4 finale airs Thursday, June 16, at 10 p.m. EDT on BBC America.

Orphan Black Krystal Sarah Sarah (Tatiana Maslany) and Krystal (Maslany) will come face to face in the “Orphan Black” Season 4 finale. Photo: BBC America Orphan Black 410 synopsis Felix (Jordan Gavaris) tries to help in “Orphan Black” Season 4, episode 10. Photo: BBC America

Orphan Black Cosima Cosima (Tatiana Maslany) and Charlotte (Cynthia Galant) seem to be in trouble in the “Orphan Black” Season 4 finale. Photo: BBC America