Jonathan Lambshead will inherit has grandfather's mansion-- after he and two schoolmates catalog its contents. They discover that the mansion's basement contains portals, with one leading to an alt-Earth called Aurora. There magic abounds, history has been re-written, and an occult dictator called Aleister Crowley leads an army pillaging alt-Europe. Jonathan pieces together his destiny as a member a secret society devoted to keeping our world separate from Aurora. But alliances shift as the trio pursue the profound evil-- and discover it is also chasing them.