The setting is an island off the southern coast of Norway where vacationers are enjoying the hospitality of a resort hotel. Following the suspicious death on the island's moors of Forestry Agent Blinde, recently engaged to the beautiful Hilde Gjærnes, master detective detective Asbjørn Krag is summoned to investigate. Krag must disentagle jealousies, deceptions, and past crimes to solve this mystery. And to complicate his investigation, Hilde Gjærnes' grandfather is killed at night on the same moor, while Asbjørn Krag is only a short distance away.
And then there is the mysterious jernvognen, an iron wagon that haunts the moors and the island. Curiously, the sounds of the wagon are heard the nights when Blinde and old Gjærnes are found dead. But, the wagon leaves no tracks in the ground and is never seen. Just what is this iron chariot?