Blood Ties

S3, E20: After discovering that the Rambaldi "Passenger" is her half-sister, Nadia, Sydney and Jack seek the aid of Nadia's father, Sloane, to track her down. Meanwhile, after learning a secret about his father from Thomas Brill, Vaughn is kidnapped and tortured by Lauren and Sark, who are hot on the trail of "The Passenger" themselves.