Edinburgh is basking in an unnaturally warm winter until the snow starts falling. When a student disappears, along with his climate research, and the national government close down all communications, Professor Finlay Hamilton realises there is a link between his own research into dark matter and the freak weather. Suddenly he is in a desperate race to save his wife, Jess, and their young family from a catastrophic event. His only help is a man from Jess's past, a past he never knew existed. Under the relentless snowfall, only the strong will survive - and Jess must be strong enough to keep her family safe.