TV Line teases that ex-“Deadwood” heroine Molly Parker is headed to “Dexter” as someone’s sibling… But whose?!

Parker will appear in several Season 6 episodes of the Showtime drama as Lisa Marshall, the sister of Colin Hanks’ mysterious new character, Travis. Sounds innocent enough, but details surrounding Parker’s role are scarce — which is like admitting guilt (it’s probably juicy!)

Hanks will appear in all 12 episodes of Dexter`s sixth season as a brilliant expert on ancient artifacts who somehow becomes linked to a series of grisly murders in Miami. It remains unclear if Travis will turn out to be a friend or foe of a certain Dark Passenger.

Here’s the official plot tease: “Dexter Morgan (Michael C. Hall) spent Season Five atoning for the death of his wife, Rita. He committed to being a part of her children’s lives and entered into a deep, passionate relationship with Lumen, unlike anything he’d ever had before. But Dexter’s need to kill overpowers his desire for human connection. And now that one person knows the truth about him, and a few others are close, how much longer will America’s favorite serial killer be able to keep his dark side a secret?”