And the Trial of the One (S04E11)

The moment has come to select the one Librarian who will bond with Baird, but the decision proves difficult for the group. In response, the Library intervenes, stripping the Librarians down to their most basic instincts and casting them into a nightmarish realm of their own fears. This is the Trial of the One, but they must find a way to reclaim their humanity before it's too late, or risk losing two Librarians and Jenkins in the process.