Artemis Fowl creates an extraordinarily powerful computer with stolen fairy technology, but his business deal hopes go sour when a Chicago businessman steals his invention and mortally wounds Artemis's loyal bodyguard.

Bounty hunter Stephanie Plum joins forces with Diesel, a fellow hunter and sometimes lover, to track down Wulf Grimoire, a wanderer and murderer with no remorse and the ability to hide in any conditions, and as the pair track the elusive criminal, they find themselves plagued by spooky occurrences and the legendary Jersey Devil.