Professing to come from the planet Ezdar and calling himself 'Bob,' the galactic visitor must remove The Key from Jason's body before a warring alien race called the Krytons learns of its true whereabouts. If the Krytons get their hands on it, it spells the destruction of Ezdar and its inhabitants.
Safely detaching The Key from Jason's heart requires Bob's spaceship. Unfortunately, Bob has no idea where they must go to rendezvous with his craft, meaning Jason must somehow locate the place where Bob will meet his ship. And if it isn't removed soon, The Key - and Jason - will die.
Along the way Bob monitors the health of Jason and The Key between attacks from Kryton Death Squads. The death and destruction left in their wake draws the attention of law enforcement and eventually Homeland Security, led by the attractive but no-nonsense lady agent, Greer.
To complicate things further, Jason comes down with a serious case of love at first sight for the pretty federal agent. All he has to do is survive his dilemma and get past her blatant dislike of him.
At the literal heart of all of this is The Key. The Ezdarians want it. The Krytons want it. The United States Government wants it. The only one who doesn't want it is Jason Hayward, who must somehow survive 72 insane hours and 1,000 hard-fought miles of self-preservation, self-defense, and self-sacrifice as The Heart of Ezdar.