Magnus Chase and the Gods of Asgard, Book One : The Sword of Summer

Magnus Chase has always been a troubled kid. Since his mother's mysterious death, he's lived alone on the streets of Boston, surviving by his wits. One day he's tracked down by an uncle he's never met - who tells him an impossible secret: Magnus is the son of a Norse god. The Viking myths are true. The gods of Asgard are preparing for war. Trolls, giants and worse monsters are stirring for doomsday.
To prevent Ragnarok, Magnus must search the Nine Worlds for a weapon that has been lost for thousands of years.