By Mallika Rao
October 07, 2010 at 10:45 PM EDT

Image Credit: David Gabber/PR Photos; Alexandra Wyman/Getty ImagesRachel Weisz and Emily Blunt are set to star as sisters in the latest project directed by indie wunderkind Lynn Shelton, according to Weisz’s reps. There’s not much else they’re revealing – no title, no plot – only the promise that the acting will be “semi-improvised,” and shot over a few weeks this coming fall. So let’s try our hand at guessing what it’s all about, shall we?

Shelton’s three previous films all feature two characters in intimate congress. In her January 2009 release, Humpday, a pair of old college buddies explore the implications of having sex with each other on tape to win an amateur porn competition. My Effortless Brilliance from 2008 features two dudes again, ex-best friends sorting out their differences in a remote cabin in Eastern Washington. And in Shelton’s first feature from 2005, We Go Way Back, a rising actress who’s nabbed a plum role is dogged by the specter of her younger self.

All good fodder for a sister flick. In considering the predecessors, here’s what I’ve come up with: Weisz’s character convinces Blunt’s to reshoot a childhood home video in a cabin in the woods. In the process, they come to understand why they love each other and themselves. And that they’re pretty.

So what about it PopWatchers: any better ideas?