Capable, responsible 13-year-old Angus and his disorganized, daydreaming, always-in-trouble 11- year-old brother Giles set out on the sparkling afternoon following a major snow storm. It was meant to be a simple cross-country-ski trek to the grocery store to restock the family's empty cupboards. But at the store they encounter the local doctor who begs them to ski up to the isolated hilltop Renshaw farm. Mrs. Renshaw is ill and alone, and has used up her vital heart medication. The doctor cannot drive there because of huge snow drifts. All phones are down, so he cannot summon a snowmobile. The only way is for someone to ski there, taking her medicine. Angus accepts. The boys reach Mrs. Renshaw, give her the needed dose and struggle in an unheated and eerie house to make her comfortable and warm. At her request they feed the hungry farm animals. It is dark and snowing hard again when they set off for home. Disaster strikes. In the woods Angus falls and breaks his ski. Pain forces him to a halt. He will freeze to death if Giles cannot proceed alone to bring help. It is now up to Giles whether they both survive.