At dusk on a November evening in 2020 a woman slips out of her garden gate and turns up the hill. Kate is in the middle of a two week quarantine period, but she just can't take it anymore - the closeness of the air in her small house, the confinement. And anyway, the moor will be deserted at this time. Nobody need ever know. But Kate's neighbour Alice sees her leaving and Matt, Kate's son, soon realizes she's missing. And Kate, who planned only a quick solitary walk - a breath of open air - falls and badly injures herself. What began as a furtive walk has turned into a mountain rescue operation . . .