Deryn's father is the lighthouse keeper on Featherstone Island, keeping the lantern lit to protect passing boats from the treacherous rocky coastline. But when an emergency arises and Deryn is left alone to keep watch over the lighthouse, she finds herself in a terrible situation when the lamp runs out of oil during a wild storm.With a fishing boat in peril on the sea, Deryn has to seek help from an unusual source. Will she be able to keep the lantern lit through the dark, dangerous night?