Showtime has announced that Julia Stiles will be joining the cast of “Dexter” for 10 episodes of the series’ fifth season.

Showtime is keeping mum on the details behind her character, save that Stiles “will play a mysterious young woman who forms a unique relationship with Dexter (Michael C. Hall) in the wake of the death of his wife.”

Entertainment Weekly’s Michael Ausiello, who first reported the possibility of Stiles’ casting last month, asked new “Dexter” showrunner Chip Johannessen about what shape the fifth season might take after John Lithgow’s memorable fourth season turn as the Trinity Killer.

“We’re not going to have a single Big Bad this season,” Johannessen told Ausiello. “We don’t want to try and top John Lithgow, so we’re going to change up the forces that Dexter’s going to be dealing with.”