Girl Power

A riotous tumble of comedy, that, like the very best films, is tempered with real emotion

YOUR SISTER'S SISTER

As this summer has so far presented us with one mandatory option of rain, it feels only fair to offer the reader a choice. If a) you'd like to see a terrific comic drama without knowing a stitch about it, take yourself off to Your Sister's Sister now and enjoy the surprise. If b) you need more persuading about a film that unrolls its story with all the flair of a diamond-studded red carpet, then carry on reading.

Emily Blunt has spoken at (polite, un-career threatening) length about the lack of good roles for women in Hollywood, and if that's what keeps pushing her towards independent films then, fingers crossed, it continues.

Your Sister's Sister is the second film from writer/director Lynn Shelton, who brought us 2009's cheerfully unusual sex comedy Humpday. It is one of those films that po-faced beards call 'deeply human'; an uncomfortable, witty, very funny study of what happens when three lives overlap too much.

Jack (Humpday's Mark Duplass, brilliant) is failing to get over the death of his brother Tom the year before. His best friend – and Tom's ex-girlfriend – Iris (Blunt) stages the sort of intervention that only works between people who know each other, and packs him off to her father's technology-free island holiday home for some time alone.

When he gets there he finds Iris's older half-sister Hannah (Rosemarie DeWitt) in situ after breaking up with her girlfriend of seven years. A tequila-fuelled night of misery-drowning, and Iris's arrival the next day, lead to a week of exquisite awkwardness and comic, all-too-real moments.

Given how 'talky' this film is, it's a delicious relief that it steers clear of self-aware clichés. Instead it's a riotous tumble of comedy that, like the best, is tempered by real emotional turmoil. Duplass's Jack nips any pretensions early on in the film when he witheringly shoots down a well-meaning hipster's eulogy of Tom as a paragon.

The rest of the party recoil from looking at Tom as a whole person, good and bad, whereas, Jack argues, that is what made him a truly great person. And Iris, Hannah and Jack are flawed but insanely likeable: whole people, good people who occasionally mess up, but care deeply about not hurting others.

Iris, who is mocked mercilessly by Jack for her habit of mercilessly short relationships with Identikit musicians, still worships Hannah, greeting her with the wide-eyed joy of a Malory Towers girl with a crush on a prefect. Unemployed, bereft Jim, is aware of the fact that he is of no use to anyone, but makes up for it with sarcasm, humour, kindness and excellent cooking. And Hannah, seemingly grounded and sensible, is just as capable of making spontaneous decisions that veer wildly off any path marked 'appropriate'.

Three people chatting on a misty, cold island for 90 minutes might not sound thrilling, but the largely improvised script keeps you rapt. Each new revelation feels original and inventive, with such a neat, apt ending that my entire cinema screening laughed.

In Your Sister's Sister, Lynn Shelton takes a recognisable setup, and reinvents it with all the skill of a cinematic Heston. I can't wait to see what she cooks up next.