Hammered (with bonus short story): Book Three of The Iron Druid Chronicles

In Hammered, the third installment of The Iron Druid Chronicles, two-thousand-year-old Druid Atticus O’Sullivan faces his most formidable challenge yet: taking down Thor, the Norse god of thunder. Despite warnings from multiple sources, including deities, Atticus feels compelled to act, compelled to ignore advice that he wouldn’t normally ignore.

His decision stems from Thor's mistreatment of others and promises Atticus has made. His quest takes him to the Norse planes, where his actions will ripple throughout the nine realms. But Atticus will not only face Thor's wrath but also navigate also a brewing turf war amongst vampires, a group of mystic hunters, and the desires of a pack of werewolves—All while trying to stay out of Thor's way.