Strange things are happening around Niklas Summerhill's home. A green-eyed beast is killing animals in the woods, and the nightmares that have haunted Niklas since his mother died grow more terrifying with every night. When the beast turns out to be a troll brought to life from his own games, Niklas knows he has to stop it. With the help of his lynx companion, Secret, he finds the source of the magic: a portal to another world. But this realm, once the home of peaceful animals, is also in danger. The evil Sparrow King is hunting down the few survivors from a devastating war, and a dark, blood-thirsty plant is infecting the valley. Niklas must try to save both worlds. But first he has to uncover the truth about his mother's last words: I'm a Thornghost.From the author of The Twistrose Key comes a fantasy brimming with intriguing mystery, fast-paced action, and a cast of unforgettable human and animal characters.