Psych‘s Skyler Gisondo has landed a lead role in Fox’s Night At The Museum 3. He’ll play Nick, the son of Ben Stiller’s security guard Larry Daley in the London-set threequel. Stiller is expected to return as is Robin Williams as Theodore Roosevelt. Downton Abbey‘s Dan Stevens just joined the cast as Lancelot. The 17-year-old whose credits include The Bill Engvall Show and Rob Zombie’s Halloween just wrapped Hard Sell opposite Kristen Chenoweth and also appears in Sony’s upcoming The Amazing Spider-Man 2 as Howard Stacy, the role he played in Marc Webb’s first Spidey pic. He’s repped by Paradigm, Wishlab, and attorney Neil Meyer.