From FOX’s official press release:

When a spy is discovered in the Dollhouse, Echo becomes Sherlock Holmes to uncover the traitor, on Dollhouse, Friday, April 10, on FOX.

When a traitor is discovered inside the Dollhouse, Echo and Sierra are programmed as spy hunters to uncover the culprit. Meanwhile, Ballard receives surprising news from Mellie, and Adelle harbors a secret in the “Spy in the House of Love” episode of Dollhouse airing Friday, April 10 (9:01-10:00 PM ET/PT) on FOX.

Cast: Eliza Dushku as Echo; Tahmoh Penikett as Paul Ballard; Olivia Williams as Adelle DeWitt; Fran Kranz as Topher Brink; Harry Lennix as Boyd Langton; Enver Gjokaj as Victor; Dichen Lachman as Sierra

Guest Cast: Amy Acker as Dr. Claire Saunders; Reed Diamond as Laurence Dominic; Miracle Laurie as Mellie; Valerie Cruz as Ramirez; Liza Lapira as Ivy; Tim Chiou as Nikoden

Source: FOX
(Image courtesy of FOX)