Claire is no longer a child! She may only be twelve, but she is the princess of Arden and the only hope for her sister Sophie, who is haunted by a mysterious illness. Claire must save her, and at the same time the whole of Arden, to which its last queen, Estelle, has returned. After all, no one except Claire knows that Estelle is evil in the flesh and dreams of destroying the last unicorn and taking away its power. And Claire cannot allow this either. She has many adventures ahead and the main test - can she find the courage and strength to unite Arden, defeat the evil queen and return her sister home safe and sound?