Magnus Chase and the hammer of Thor / Rick Riordan.

My name is Magnus Chase. Two months ago I died fighting a Fire Giant and woke up in Hotel Valhalla as one of Odin's warriors. When I meet Otis, an informant with a lead on Thor's missing hammer, all I get is the name Provincetown before a wolf-masked assassin takes him out and warns me to stay away. Someone really does not want me to find the hammer, and even if I could it is rumoured to be underground, guarded by powerful magic. But the giant armies are on the move, preparing to invade. If I do not find it, they will ravage the Nine Worlds, starting with the streets of Boston. There is just one person who could help. Someone who demands a very high price: the gods' worst enemy, Loki.