Your Sister’s Sister

The new Lynn Shelton film, her first since “Humpday,” stars Emily Blunt and Rosemarie DeWitt as a pair of sisters, Iris and Hannah, and Mark Duplass as Jack, the guy—clever, a little lumbering, and much less happy than his manner suggests—who gets stuck between them. Taking time out at a vacation cabin, on a quiet island, he finds that Hannah has got there before him; he is still mourning a lost brother, and she is just emerging from a lesbian relationship, so it seems only natural, if disastrous, that the two of them should bicker, drink, compare emotional scars, and go to bed. When Iris appears, apparently beatific but with frustrations of her own, the stage is set. The movie is a piece for trio, and Shelton shows plenty of finesse in the orchestration of their movements. So low-key is the look she aims for, and so halting and unrefined the dialogue, that the outcome strays now and then to the borders of the merely glum; but all three performers add both tone and, when required, a fierce volume to their interplay. Do we honestly believe, however, that everything could—and should—be resolved with quite such ease and hope?