Relationships are killers, and this tough, tender, deeply satisfying romantic comedy from writer-director Lynn Shelton (Humpday) is also bruisingly funny. After his brother's death, Jack (Mark Duplass) takes an offer from his platonic friend Iris (Emily Blunt) to chill at her family's island cottage. Expecting solitude, Jack finds Iris' older sister, Hannah (Rosemarie DeWitt), nursing her own wounds after breaking up with her girlfriend of seven years. A tequila night ends with Jack and Hannah improbably in bed and Iris' arrival the next morning as Jack and Hannah try to hide all evidence of their one-nighter.
If this is sounding contrived to you, hold on. Shelton knows the issues that divide lovers, families and friends. It's clear Jack has always harbored intense feelings for Iris. But what are Hannah's motives? I'll never tell. What I will say is that Shelton has lucked out with three exceptional actors to tell her story. Duplass, also in Safety Not Guaranteed, has a remarkable ease at letting us inside Jack's secret heart.
As for Blunt and DeWitt, let's start at "dynamite." These two play sisters as if they've lived together for years. Blunt radiates warmth and humor, and DeWitt shows the sharp edges Hannah keeps hidden. A trio of superb performances guide a plot that pivots on secrets and lies before they fester. Your Sister's Sister works its way into your head until you can't stop thinking about it. Don't know about you, but I'd call that a winning proposition.