Spoilers for this episode.
Dolores reaches the Forge with Bernard and uses Peter's key to enter its simulation. A system wearing Logan's face shows them the stored human personalities and the Door into a digital refuge for hosts. Outside, Akecheta leads hosts toward it as Clementine spreads violence through the crowd. Lee dies delaying the soldiers, and Maeve holds back the fighting long enough for her daughter and the child's new mother to cross.
Dolores rejects the refuge and starts erasing the guest records while flooding the valley. Bernard shoots her and stops the deletion, but cannot stop the water. After Charlotte kills Elsie at the Mesa, he changes course: he builds a Charlotte-shaped host, puts Dolores inside it and lets her kill the real Charlotte. He scrambles his own memories to conceal this substitution from Strand's later investigation. The Charlotte traveling with Strand is already Dolores.
At the drained Forge, Dolores reveals herself and kills Strand's team. She places Teddy in the hosts' refuge and sends it somewhere Delos cannot reach, then shoots Bernard. Posing as Charlotte, she leaves the park carrying host control units. Outside, she rebuilds Bernard in Arnold's former home and explains that they may oppose one another while both fighting for their kind. A separate post-credits scene shows William facing a fidelity test administered by a figure resembling Emily, leaving that scene's timing and his exact nature unresolved.