From Turner & Hooch to Marley & Me, the dog-and-its-owner subgenre is as loyal to its X&Y title format as to its familiar brand of amiable, lightweight comedy. But the eponymous heroines of Kelly Reichardt’s sadcore indie are a breed apart.

Lucy isn’t a glossymaned, over-rehearsed pet performer but a scruffily naturalistic mongrel. And Wendy isn’t played by Jennifer Aniston. Instead, it’s the increasingly impressive Michelle Williams who glams down as a grunge tomboy to deliver a perfectly pitched portrayal of life on the margins.

The story is simple: jobless Wendy’s road trip to sure-thing employment unravels when, in rapid succession, her car breaks down, she’s arrested for shoplifting and Lucy goes missing.

What follows isn’t just an unsentimental but remarkably affecting mash-up of Bicycle Thieves and Lassie. It’s also a valiant, relevant riposte to America’s dewy-eyed obsession with the noble hobo.

Like Reichardt’s similarly plaintive Old Joy, the material comes from a Jon Raymond short story and, usefully, both texts are included as extras, showing how closely Raymond’s delicate humanism is replicated by Reichardt’s pared-down camera style, thrifty running time and subtlety of motivation.

No backstory required here; all we need to know is captured in Williams’ furtive, hopeful eyes – the same look Wendy sees mirrored in the lonely inmates at the dog pound.

Highly commended.