Life itself suddenly sees full of woe for 17-year-old Sam Alden. Home for a traditional Christmas celebration, the usually robust young man worries his family with his drawn appearance and persistent coughing. Subsequent tests reveal the cause - degenerative heart disease. His condition rapidly deteriorates until his doctors determine that only a heart transplant offers him any hope for prolonged survival.
Putting aside their own fears, Sam's large, warm, loving family rallies around him. Drawing strength from each other, and from an enthusiastic, optimistic Sam, his mother and father take turns keeping watch with him - awaiting decisions that could give him the chance to fulfill the promise of Thursday's child.