On a blazing hot summer's day, holidaymakers on a Norwegian island are shocked to discover that a fellow guest has been found murdered on a desolate plain. The nameless narrator, an author, was the last person to see the victim alive; shortly afterwards, he was disturbed by a noise like "a rattling of chains." A local tells him this is "the iron chariot," said to presage death. Detective Asbjorn Krag is summoned from the capital to investigate. When a similar death occurs on the plain, it is again preceded by the eerie sound. Mystery is added to mystery when the victim turns out to be a man believed to have died several years earlier. Drawn unwillingly into the investigation, the narrator is puzzled by the enigmatic detective's apparent inaction, and troubled by unfolding events. So profound is his unease that he feels he must leave the island. Then Krag promises to tell him the solution to the mystery.