Prophet Five is the 1st episode of Season 5 of Alias and the 89th episode overall. After learning that the man she has known as Michael Vaughn is under investigation and suspected of being a double agent, Sydney begins to question whether their business and personal relationship over the years had all been a lie. When she discovers that she's pregnant with Vaughn's baby, she becomes determined to uncover the truth about him. Meanwhile, because of Jack's past betrayal by Irina, he begins to worry that his daughter may suffer the same fate that he did.