A twelve-year-old from Ohio finds a compass in his late grandfather's storage unit. It opens a gate to a Norse fjord, deposits him next to a sea serpent, and assigns him a three-tailed fox named Nyx as a guide - whether he wants one or not.
The compass, it turns out, belongs to whoever it chooses. And it has chosen Eli to continue work his grandfather started and never finished: tracing a two-thousand-year-old pattern of deliberate damage to the fabric of dimensional reality. Someone has been quietly dismantling the infrastructure connecting every mythology, every world, every god - and doing it so slowly it looks like entropy.
Eli's first three days take him from Ohio to Asgard, from Asgard to a bureaucratic Mount Olympus where he fixes three administrative problems no one had bothered to check in four centuries, and from Olympus into the Veil - the dark in-between space connecting all dimensions - where a market has existed since before most worlds did. There he meets Moth, an information broker who has been tracking the same deterioration for longer than most living things have been alive, and recovers a letter his grandfather left for him.
The letter confirms the pattern is real and names someone called Mara, as the one person who understands its full shape.
He is still on day three. He has time.