Director Kelly Reichardt's western is set in the open-skied, arid wilderness of Oregon in 1845, and follows the fortunes of three families seeking the promise of a better life.
The voluble Stephen Meek (Bruce Greenwood) has persuaded his fellow travellers that he knows a short cut, and so, keen to lessen the grim rigours of their trek through the harsh landscape, the small band have left the established trail.
But, despite Meek's frequent assertions that he does know how to safely get them across Native American territory, his authority as guide gradually starts to be questioned.
Slowly it dawns upon the pioneers that their water will run our long before Meek's self-confidence.
And it's at this point that they run across a Cayuse tribesman (Ron Rondeaux) and that Emily Tetherow (Michelle Williams) decides that placing any further trust in Meek will surely see them all die a lonely, parched death.
Unfolding almost in real time, Reichardt's drama certainly gives the viewer a good idea of quite how arduous - and dangerous - pursuit of the American dream could be in the middle of the 18th century.