Plot summary
Ferdinand rescues Rachel from Dyad. Though Sarah is suspicious, Siobhan wants everyone to focus on the opening of Felix's art show that night. Siobhan and Delphine are revealed to be working with Ferdinand as a source. Their efforts have finally figured out Neolution's ultimate goals but they need hard data from Rachel to prove it all and warn the world. Ferdinand says he and Rachel can use this to blackmail Westmorland's backers and build an empire. Rachel betrays him and gives the real data to Siobhan to bring down Neolution.
Delphine and Cosima then upload it. Sarah, Alison and Cosima become performance art posing as one person in Felix's show. Felix thanks his family for their support, especially Siobhan for taking him and Sarah in as children. Meanwhile, Gracie decides not to betray Helena but the Neolutionists trace her phone, capturing Helena, and Detective Engers kills Gracie. Ferdinand attacks Siobhan in her home and the two kill each other. Sarah senses Siobhan's death.
Credits
Adapted from Wikipedia contributors, List of Orphan Black episodes. HTML formatting and reference markers removed.