Something strange is happening to the woods and water around Niklas Summerhill’s home: Animals are dying, Niklas’s grandmother doesn’t seem like herself, and his uncle is suddenly lost in grief over his sister, Niklas’s mother, who died seven years ago. When Niklas discovers an ancient key, he and his talking lynx companion, Secret, leave home behind to travel to a different realm. But this realm, populated by animals, is in danger as well: A tribe of evil trolls is wreaking havoc, a mysterious enemy called the Sparrow King is bringing his wrath down upon the animals, and the Rosa Toraquata, the root that connects this realm to Niklas’s own, has developed a dark twist that is infecting the land. Can Niklas and Secret save the animal realm—and their own?