Abbie's father, the lighthouse keeper, must go for supplies, medicine, and oil. As he leaves, he asks for Abbie's promise to keep the lights burning. She gives her word and watches him row away, not knowing that a storm will soon isolate the lighthouse for four weeks. She learns what a promise means as she tends the lights nightly, cares for her sick mother, her sister, and her chickens, and watches anxiously for the storm to end. Based on a true story.