Gaiman's novel takes place in a world where mythical gods exist to the extent that people believe in them. The entire book is a discussion of the power of thought and persuasion. In a sense the questions raised relate to the nature of reality. Can it be trusted? Can we control our own existence?
The story's protagonist, Shadow, is a recently released convict. Upon his release, he learns that both his wife and his best friend have died in a car accident. Not in the most stable place mentally, Shadow finds himself taking a job for a mysterious man named Wednesday, who turns out to be Odin himself. Quickly realizing he's out of his league, Shadow is swept up in a war between two generations of gods -- the young iconoclasts who advocate for technology and the older, traditionalist gods. He engages in a series of epic fights and adventures, during which he is able to resurrect his wife, loses Odin, and grows close to an attractive woman named Laura who seems to know a great deal more than him about what is happening.
The tipping point of the story is Odin's death. Shadow discovers that he is actually Odin's son. Confused and alarmed, he wrestles with a million questions, namely whether or not his entire collection of experiences after prison were a scheme to place him in a position to become Odin's heir. Still not entirely sure he believes in a world of magic and reincarnation, Shadow finds himself becoming a leader amongst the divine community. He is called upon to defeat the younger generation of gods.
The irony is that Shadow isn't persuaded that anything he's experiencing is real or not, but he's supposedly the one feeding the delusion. Is he having a mental breakdown, or is his belief in the beings he meets somehow perpetuating their existence? The story alludes to how some people believe Santa Claus possesses magical powers, according to the measure of children who believe in him. Only Gaiman is dealing with existence rather than solely magic. Solely able to determine for himself which experience to credit as truth and which to remain doubtful concerning, Shadow becomes the master of his own existence by his very recognition of his state of existence.
