S4, E20: After learning the awful truth about Nadia's childhood caregiver, Sophia (Sonia Braga, "American Family," "Kiss of the Spider Woman"), APO races to track her down while an agent's life hangs in the balance. Meanwhile Sydney and Nadia question Sloane's trustworthiness now that his obsession with Rambaldi may have been renewed, Jack has an unsettling meeting with Katya Derevko (Isabella Rossellini), and Vaughn asks Jack a surprising and momentous question. Angela Bassett guest stars as Hayden Chase.