Lucas had no intention of becoming friends with Ella, the girl who claims that the missing professor who used to live in Lucas' house is her grandfather. But Ella is such a pain, and now she is already walking next to Lucas, Rani, Felicita and Punhi in the Whispering Forest. They must find the professor and save him, and at the same time unravel the mystery of the mysterious Heart of the Forest and its powers. And even though, following the clues, they must descend into a lava-flooded dungeon, fly up to a city in the sky and dive into a lake infested with monsters, friends know that they cannot retreat, no matter what surprises the Whispering Forest, full of magic and wonders, has in store for them.