Magnus Chase and the Hammer of Thor

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. Time for a rest? I wish.
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 doesn't want me to find the hammer, and even if I could it's rumoured to be underground, guarded by powerful magic.
There's just one person who could help. Someone who demands a very high price: the gods' worst enemy, Loki.