There's not a lot to say about Your Sister's Sister. It's a simple, little indie movie without a lot of story going on. With one exception -- near the end -- the movie isn't artificially plot-driven. In fact, there's really nothing about this movie that feels artificial. And, that's its appeal.
The movie opens on a memorial service one year after the death of Jack's (Mark Duplass) brother. Jack, obviously having difficulty dealing with conflicting emotions about his brother, goes to great lengths to remind the gathered friends that his brother wasn't always such a nice guy. Jack's best friend Iris (Emily Blunt) -- who, incidentally, dated Jack's brother at some point before he died -- offers her assistance by giving Jack access to her father's cabin for the weekend.
So, Jack takes a ferry and makes his way to the cabin, only to find it occupied by Iris's sister Hannah (Rosemarie DeWitt). After a humorous meeting involving underwear and a weaponized oar, Jack and Hannah figure out the confusion and settle in for a quiet weekend spent on opposite sides of the cabin.
Unable to sleep, Jack and Hannah eventually sit down together to commiserate about each other's problems. Hannah, it seems, has just recently left her girlfriend of many years and...well...you know Jack's problems. After several drinks, the two of them decide, as is often the case in movies such as this, that it wouldn't be a bad idea to have sex. After all, Hannah's a lesbian, so there's no chance of emotional attachment, and Jack's not attached to anyone. They awake the morning after their drunken encounter to the sound of Iris coming into the house.
Jack, at first, is nervous, though it's not clear why. Iris isn't his girlfriend and, once again, there's no chance of romantic entanglement. The situation is odd, but not fatal. Later, after learning some important information, Hannah shares Jack's fears. What follows is a character study of three people in an awkward situation sharing a cabin. It's not flashy, it's just very well done.
