EXCLUSIVE: Downton Abbey star Dan Stevens has been cast as Lancelot in Fox‘s Night At The Museum 3. This is a pivotal role in the film, which is set in London. Ben Stiller is expected to return as museum security guard Larry Daley and Robin Williams is in talks to return as Theodore Roosevelt. Shawn Levy is expected to return to the director’s chair in his signature franchise which has grossed north of $1 billion. Production is expected to begin early next year.

Stevens was just seen in The Fifth Estate, and next stars in Adam Wingard’s The Guest. He’s co-starring with Liam Neeson in A Walk Among The Tombstones for director Scott Frank.

Levy just completed the Warner Bros dramedy This Is Where I Leave You, which stars Jason Bateman, Tina Fey, Adam Driver, Jane Fonda, Rose Byrne, Timothy Olyphant and Katherine Hahn. Levy just produced the indie hit The Spectacular Now and the recently wrapped Alexander And The Terrible, Horrible, No Good, Very Bad Day, the Miguel Arteta-directed film that stars Steve Carell and Jennifer Garner. Stevens is repped by WME and Julian Belfrage Associates.