Atlas Bain is a thoughtful, clever child, but when the lights go out one stormy night, he finds he's in for a bit of a fright.  Is it all in his imagination, or are the mishappenings real?

The good Duke Jean rules peacefully over Brittany, but enemy magical forces seek to undermine his power. As the sovereign prepares a journey to meet his people, Knight Charrette is tasked with going ahead as a scout to thwart the spells scattered across the country's roads. A quest that will see him face sorcerers and malevolent ghosts, blacksmith giants, dragons, and other dancing korrigans... These tales travel across the nine historic lands of Brittany, carried by a knight who, if not the bravest, is always the cleverest. Knight Charrette, nothing ever stops him!

Sensitive, and the Benevolent must defeat the tyranny of the Grand Council of Druids, which is bent on destroying all the magic in their world. But they cannot do it alone.

Aided by the Keepers, they try to rally the mysterious king of the elves to their cause by traveling to the legendary Mother-Tree, the Heart of the forest. The resistance is underway, carried by the song of the inhabitants of the Black Paths. The siblings also discover the secret of the birth of the oak tree Yggdrasil and must face a terrible truth...

Will the three children succeed in fulfilling their destiny? By traveling to the mysterious castle on the sea, will they manage to restore the balance between shadow and light?