At dawn

A man's body is found on the banks of the Calumet River, apparently murdered in a ritualistic and very brutal way. Addie Bisset, a detective with the Chicago homicide division, seeks help from her friend Dr Evan Wilding, a university professor and forensic semiotician.

But Evan isn't the only expert to be involved in the case, and the collaboration doesn't yield the expected results. Evan gradually uncovers symbols and clues, trying to decipher and correctly interpret messages written in runic script. From the riddles left by the killer, nicknamed the Viking Poet, it's clear there will be more victims.

At first, the police and Evan are unsure whether the killer is choosing his victims to honour the gods or to punish them for their sins. When they finally manage to uncover the motive, they find that Evan's life is also in danger. And so begins a race against time, which grows shorter verse by verse.