Mader, 34, will play Abigail, an elusive con woman who blackmails Neal (Matt Bomer) into getting involved in her latest heist. At the same time, she is trying to woo Diana (Marsha Thomason), who is working undercover to bring Abigail to justice. Uh oh! What will Diana's girlfriend, Christine, say about this?
Aside from her role as Charlotte Lewis on Lost, Mader is known for playing Morgan Gordon on All My Children. She recently co-starred on ABC's short-lived Work It, and will appear in the final two episodes of Fringe's current season.
Season 4 of White Collar premieres on Tuesday, July 10 at 9/8c on USA.