Lucky Luke and his friend Waldo are looking for Jasper, the former Waldo servant, who hasn't given a sign of life in months. They arrive in Dyea, Alaska and then go to the Klondike, Dawson City, where Jasper had gone prospecting. A suspect draws their attention. He is Soapy Smith, a crook with an unscrupulous owner who could be responsible for Jasper's disappearance.