Plot summary
With their hope of a cure gone, Sarah and Cosima both attempt to come to terms with their input in the deal that led to Kendall's death. Alison pushes forward with Gemma's birthday party to maintain a sense of normalcy. Susan returns to the Island and informs Rachel of the creator of Neolutionism, Dr. P.T. Westmorland, noting that he built the facilities they live in over a century ago. Mrs. S disowns Sarah who begins to spin off the rails, drinking, partying and taking drugs. Sarah's story starts to parallel Beth's and she begins to hallucinate her.
Art confirms that it was Detective Duko who killed Kendall and proceeds to attack him. Duko tells him that Neolution is after Art next. Evie has pending approval for her gene therapy technology and plans to dismantle Leda for their assets, cutting loose naive clones and terminating the self-aware clones while refusing to allow Rachel to take a position of importance within Neolution. Police interrupt the Hendrix slumber party and arrest Donnie on suspicion of narcotics trafficking. Duko then shows up and ominously says that he and Alison will be staying in touch.
Sarah finds herself at the train station where Beth killed herself, conversing with her one last time. Cosima decides to experiment on herself by inserting Sarah's bot (which she stole from Brightborn) in her own cheek, as it could cure her, or her death could help the Leda clones learn about the disease. Felix talks Cosima out of it, informing her that Krystal saw Delphine get carried away alive after being shot. Felix then arrives at the train station, where Sarah contemplates jumping. He and Beth's apparition talk Sarah out of it, and she steps down and returns to Mrs. S's home. M.K. hacks Kira's computer. Kira calls her the girl in the shadows. Rachel sees a swan in her prosthetic eye.
Credits
Adapted from Wikipedia contributors, List of Orphan Black episodes. HTML formatting and reference markers removed.