Ragi is given the chance to find a wonderful treasure, "nine times more splendid than anything else ever found anywhere in the North Lands"! But there's a big problem, for the treasure is hidden inside one of the mysterious, haunted `troll-mounds' that are dotted all over the islands.
Ragi involves two girls, Unn and Kadlin, in his treasure-quest... But they get him into really deep trouble. He finds himself condemned as an outlaw and banished to the wilderness!
There's only one person who could help him survive - and that's Grim Gruesome! But how can Ragi possibly dare to trust him?
Hold your breath as the three children survive thrilling adventures in tiny boats, and being locked inside the troll-mound! Shiver when they stumble on human skeletons! Marvel at the mysterious powers of the seals who live in the sea around the islands! Be amazed by the astonishing treasure the children find! Cheer them on in their final battle against Grim Gruesome!