Ethan Gage wants to enjoy the fruits of victory after helping Napoleon win the Battle of Marengo. But an ill-advised tryst with Bonaparte's married sister has made that impossible and he flees to America, accompanied by the wild Norwegian Magnus Bloodhammer.

With President Thomas Jefferson's blessing, Ethan and Magnus embark upon an expedition into the western wilderness – keeping their eyes open for woolly elephants. But another prize secretly impels them: Thor's mythical hammer, allegedly carried to North America more than a century before Columbus. Gage's skills will be tested as never before as he braves unimaginable peril en route to the most incredible discovery of all time.