I think it’s the doughty underdog/triumph of the spirit thing.
Lovely mildly hippy couple, in love since their teens, restore a ruined farmhouse and its land with their own hands and raise two children there and it’s their only income source, only to lose it after years of dogged legal fighting, because of their own trusting nature, the friend who betrayed them, Big Business and a legal loophole (not understood by little people representing themselves against Big Business and the other dude’s clever lawyer, whose hand Moth still shakes after they’ve lost everything), and, as if it isn’t enough that they’re about to be homeless, the husband gets a terminal diagnosis two days later.
And they have nowhere to go, no one willing to take them in, and are literally hiding under the stairs with the bailiffs pounding on the door when they decide, in desperation to do something magníficently brave and odd, rather than knuckling down, doing the banal thing, and getting jobs and living in council emergency accommodation, because he’s going to die within a couple of years and she can’t bear not to be with him every second they have left. And he can’t even put his own rucksack on at the start, and they have only £48 a week to feed themselves, and sometimes that doesn’t come through, and he runs out of his drug, and the path is brutally hard, and they’re starving and watching other people heartlessly chomp through cream teas and be horrible when they say they’re homeless, and once or twice they steal because they’re desperate, but they share what little they have with anyone else poor etc etc. But gradually, nature is sustaining, and the sick man gets much better…
It’s got everything.