WARNING: Norse mythology purists may want to stop here, because this book takes some serious liberties with stories about the Norse gods. May cause myth-fan-rage. 
 But aside from some mythic "reimagining," Tessa Gratton's "The Lost Sun: Book 1 of United States of Asgard" is a clever, richly-fantastical fantasy, set in an alternate history where the Americas were colonized not by the British and Spanish... but by the Scandinavians and their gods. Part urban fantasy, part alternate history and part magical road trip, this is a bittersweet, powerful story about a boy's fight against fate. 
 At the school of Sanctus Sigurd, Soren Bearskin is an outcast -- his berserker father went on a random killing spree, and Soren is doomed to become a berserker as well. So he seems an unlikely companion for beautiful Astrid Glyn, the daughter of America's most famous seethkona -- but both of them can tell that they are bound together by fate. If only her presence didn't make his berserker blood get hot. 
 Then on the day when Baldur the Beautiful is supposed to rise from the dead... he doesn't. The country is thrown into a panic, and Odin Allfather offers a favor to anyone who finds Baldur. 
 Astrid decides to track down Baldur with her seething magic -- if they find him, Odin can tell her where her missing mother is, and lift the berserker curse from Soren. But though they are able to find Baldur, he's unable to remember who he is. And as the teens drive the amnesiac Baldur to the other gods, Soren begins to realize that all of this was orchestrated. 
 Tessa Gratton is one of those rare young adult authors who has a truly captivating writing style -- her prose is jewel-toned and rich with atmosphere ("thin shafts of starlight like ghosts in the rafters," "frost glimmers like diamonds from the tips of the grass"), full of bright fires and eerie smoke-filled nights. It gives a real sensuality to the story, filling it with bright sounds and lush smells. 
 It also works well with this alternate version of the U.S., which has a Scandinavian-derived culture instead of Anglo-derived. Not only are the Norse gods real and visible in this world, but each group of their devotees has a sort of subculture based around their worship. And there are some cute "modern" depictions of a magical Norse culture -- a girly magazine called "Teen Seer," holmgang-themed websites, Hallowblot instead of Halloween. 
 But it also has some flaws. It's not really explained how a fifty-state democratic country could be generated by a different culture, or how famous historical figures like Thomas Jefferson could have the same role in this alternate history. And... well, Gratton changes some of the mythological stories, such as turning Fenrir the wolf into a pretty girl. Some readers will care about this, some won't. 
 However, Gratton does an excellent job with the characters. She handles the instant attraction between Soren and Astrid beautifully, weaving in a genuine connection that makes their love plausible. Soren himself is a likably brooding figure who doesn't want to be like his murderous father, while Astrid is the perfect counterpoint -- a bright, sweet girl who dances through her magical frenzies. 
 "The Lost Sun" plays fast and loose with mythology, but it's in service of a lusciously-written story with some powerful teen protagonists. Despite its flaws, an exquisite piece of work.