Sienna Guillory has joined the cast of BBC and BBC America's "Luther," which is mostly just a way of teasing that "Luther" has finally begun production on its long-awaited third season.

Shooting on the four-episode "Luther" season began last week and will premiere in 2013.

Guillory ("Resident Evil," "Virtuality") will play Mary, a clothes shop worker who becomes a potential love interest for Idris Elba's John Luther.

"You realize why 'Luther' is so good when you read Neil Cross' scripts, and then you meet Idris and understand what 'untamed' means. There is no other set I'd rather be on, and I love the disastrous fun of being Mary Day, the right girl in the wrong place," blurbs Guillory.

Adds Elba, "I want to thank the fans for waiting so patiently for the new season. We’re thrilled to deliver it to you. Here comes John!"