December 1962, the West Country.

In the darkness of an old asylum, a young man unscrews the lid from a bottle of sleeping pills. In the nearby village, two couples begin their day. Local doctor, Eric Parry, mulling secrets, sets out on his rounds, while his pregnant wife sleeps on in the warmth of their cottage.

Across the field, in a farmhouse impossible to heat, funny, troubled Rita Simmons is also asleep, her head full of images of a past life her husband prefers to ignore. He's been up for hours, tending to the needs of the small dairy farm he bought, a place where he hoped to create a new version of himself, a project that's already faltering.

There is affection - if not always love - in both homes: these are marriages that still hold some promise. But when the ordinary cold of an English December gives way to violent blizzards - a true winter, the harshest in living memory - the two couples find their lives beginning to unravel.

Where do you hide when you can't leave home? And where, in a frozen world, could you run to?