There is little revelatory about Your Sister's Sister. The combination of deep emotional trauma and dishonesty -- with yourself and toward others -- can often create a toxic combination. Treading new ground is not a prerequisite for a worthy film, though. Were it, we all might as well quit going to the movies at all. No, successful movies are made in their details.
Your Sister's Sister is well cast and it brings modern twists to its staid theme. A love triangle is at the center of the film's conflict, though it's about as unconventional as you can imagine. Jack (Mark Duplass) is still reeling from the death of his brother a year ago, so his close friend Iris (Emily Blunt) encourages him to take time pull himself together, shuttling him off to her family's vacation home in Washington state's Puget Sound. Jack reluctantly agrees to go, but when he arrives, he is surprised to find Iris' half-sister Hannah (Rosemarie DeWitt) squatting at the house as well.
Hannah, who is staying there unbeknownst to the rest of her family, is toting her own emotional baggage, coming off a break-up with her long-time girlfriend. Her and Jack share little in common other than a general gloominess, but that and a bottle of tequila are enough to get them into bed on their first night in the house together. This wouldn't be all that big of a deal were it not for three things:
- Iris is about to surprise both of them by showing up at the house herself in the morning.
- Jack carries a flame for Iris, and, little does he know, but she feels the same way.
- Hannah's desire to be a mother helped precipitate her break-up, a fact which she deliberately concealed from Jack when they slept together.
When Iris shows up, the latter two facts combine to create this unbearable, wonderful tension. Everyone is in the wrong in some way, even Iris, who has let Jack twist in the wind, relying on him for emotional intimacy as she has dated zero after zero after zero. And all that tension comes to a boil when a suspicious Jack goes diving through the trash in search of the condom he and Hannah used and discovers that it was perforated.
It is at this point that Your Sister's Sister loses points for realism and you basically have to decide if you want to keep going along for the ride. In real life, this is an untenable situation. In real life, Iris and Hannah might be able to repair their relationship to certain degree. Iris and Jack would have absolutely no shot. In the movies, though, anything, even this, is reparable. I decided to go with it because, well, I like Blunt and Duplass and especially DeWitt, who is, at least nominally, the bad guy here, and yet plays her character with such subtle and sympathetic affliction.
I'm glad I took the ride, but I'll understand if you don't feel the same way when you get to that point. One note about the end: if you've read my reviews, you know how skeptical I am of of open-ended conclusions. Your Sister's Sister goes to that well, and I think it works because it undermines ever so slightly the seemingly happy ending, thus acknowledging the shaky detente Iris, Hannah and Jack are able to achieve. Again, it might not work for you, but it did for me.