Alias - Season 4 Episode 17 -

Nadia's former caretaker, Sophia, has been severely beaten. She contacts Nadia and asks to meet her. Sloane is told by Sophia that she was beaten up, because someone is trying to track Nadia down, so he and Jack decide to tell their daughters the truth. It turns out that Elena Derevko, the third and the cruelest of the Derevko sisters, has been surveying both Sydney and Nadia for a decade. Meanwhile, Jack's doctor advises him to tell Sydney about his illness.