Emily Blunt and Rachel Weisz Sisters for Shelton

Gorgeous actress Rachel Weisz is set to play the sister of the equally gorgeous Emily Blunt in director Lynn Shelton’s new semi-improvised and as-yet-untitled project reports Deadline. I think the fact that these two will be starring in the film will be sufficient enough reason for many to be drawn to see it no matter what it’s about.

Shelton is an American director who’s fairly new on the scene. She wrote and directed last year’s well-received “bromantic” comedy Humpday. Her other film credits as a director include My Effortless Brilliance (2008) and We Go Way Back (2006), which she also wrote. Shelton recently directed an episode of Mad Men and has signed on with Focus Features to direct Then We Came To The End, an adaptation of the Joshua Ferris novel to be produced by Ted Hope and Anne Carey’s production company This Is That. It’s the story of copy writers at a Chicago ad agency when the dot-com bubble bursts in 2001.

Shelton’s film project with Blunt and Weisz is only going to take a couple of weeks to shoot, which was the only way Weisz could have squeezed it into her busy schedule, after spending one week on Terrence Malick’s untitled new film, and before Terence Davies starts shooting The Deep Blue Sea in November.

Blunt has also been keeping pretty busy. She recently signed to star opposite Joseph Gordon-Levitt and Bruce Willis in Rian Johnson’s Looper. In March 2011, she’ll star opposite Matt Damon in sci-fi mystery The Adjustment Bureau.

Steven Schardt, who co-produced Humpday, will produce Shelton’s film starring Blunt and Weisz. Production starts later this month in Seattle.