It’s difficult to talk about the game-changing second act of writer Justin Lader and director Charlie McDowell’s THE ONE I LOVE. The film has a plot development so audacious, it makes you think of Jeff Daniels’ character stepping out of the cinema screen in THE PURPLE ROSE OF CAIRO. Marketing the film will be a challenge; if I throw a few superlatives around like ‘witty’, ‘inventive’, ‘intriguing’ and ‘Mark Duplass’ it might help.

Duplass is the go-to guy for American independent cinema. He can get it done. So when McDowell approached the actor to play the part of an errant husband in couple’s therapy, he not only got Elizabeth Moss (MAD MEN, TOP OF THE LAKE) on board as his co-star, he gave McDowell the confidence to plough ahead with the film with the minimum of resources.

Here’s what they had to play with: a house, with an adjoining guest house and a sound studio. If they can make a film with just that – great, fantastic!

It’s not quite just that. It begins with Ethan (Duplass) and Sophie (Moss) breaking into a stranger’s garden to use his swimming pool, reliving a courting memory full of fun and excitement. First time around, they got caught. Second time around, the owner isn’t in. Bummer! On the couch in the office of their therapist (Ted Danson) they complain, metaphorically speaking, that the bounce has gone from their bungee (a quote from a WALLACE AND GROMIT short, I know). Therapy guy gets them to play a synch exercise: each of them has to hit a key on the piano at the same time. Sweet music does not emerge. (What do they expect? It’s two notes; you can’t even write a rock song with that!) So their therapist sends them to a remote house. Couples who go there come back happy, refreshed. Sophie, who is the wronged one, says OK.

First thing to say about the house: it’s like half a Bel Air mansion. You expect the BLING RING to turn up at any time. Attractively furnished, with a stocked wine cabinet, it is like the ultimate middle class holiday home, minus a tennis court and a gym. Of course, a great house can’t paper over the cracks in the relationship, not least because this is an independent movie and they cannot play their favourite music owing to rights issues. (‘Hotel California? That would double the budget.’) The film does have something in common with the horror movie. Sophie is drawn to activity in the guest house and then...

THE ONE I LOVE explores the self that we lose after the initial excitement of ‘meet cute’ gives way to ‘who’s gonna to drive the kids to school?’ When we meet someone for the first time, we are eager to impress and show off our stuff; afterwards we are twenty per cent less fun. I don’t know if that’s the actual percentage, but once one person cares for another, job done. Of course, you miss the excitement of the puppy love phase. Can you truly reproduce it with the same person?

You might expect that the film with this topic is a real drag, but THE ONE I LOVE is all the things I said it was, plus ‘audacious’, ‘super fun’ (a quote from FRANCES HA, I know) and finally ‘satisfying’. Duplass and Moss are an attractive couple and give good performances; he’s the kind of guy you would imagine manages a micro-brewery or runs a liberal website, THE GRUFFINGTON POST. She is like a star reporter who transformed said liberal website. (I have no ideas what their characters do, really; they could be Arizona homesteaders.) I could think of a tagline: ‘COUPLES RETREAT minus Vince Vaughn’. Come on! Highly recommended, I hope enterprising distributors pick it up, though it doesn’t have the ‘you’ll laugh, you’ll cry’ kick of a traditional Sundance Film Festival pick-up cross-over hit.

Screened at Sundance London, Sunday 27 April, 12:00 Midday, Cineworld O2 North Greenwich, ‘Sky Superscreen’