A protracted volcanic winter has devastated Earth and left only isolated pockets of survivors. With food becoming scarcer and the air growing toxic, Rab sees just one chance for survival: a perilous journey north in search of a fabled city that was rumoured to be one of the many staging areas where ships were launched, ferrying vast numbers of the people of Earth to a salvation planet. But Rab didn’t count on being forced to take along the last three children from his dying village.
When one of the children breaks his leg, they are rescued by the hostile and sceptical Sunny, and taken by her to an underground refuge where she, her grandfather, and other refugees survive in comparative luxury. But it is a luxury teetering on the edge of collapse, and when Sunny’s grandfather begs to join Rab’s party, Sunny, to Rab’s dismay, insists on coming with them. Leaving two of his party behind Rab heads north again. With him is Gift, the young girl from Rab’s village, Sunny’s grandfather and Kix, the old man’s ancient horse, the last of its kind. Leading the way is Sunny, antagonistic and prickly. Years ago, Sunny had been the lone survivor of a similar quest.