Charlie Bone and the Shadow — Jenny Nimmo

The enchanter Count Harken is back to take his revenge on the Red King's heirs, starting with Charlie Bone's family! Charlie's ancestors have been kidnapped and imprisoned in the dark, forbidding land of Badlock, and it's up to him to save them. Traveling through a painting to the terrifying countryside, Charlie and his best friend's dog, Runner Bean, take up the quest. But when Runner Bean gets stuck in the painting, Charlie needs the help of his friends. Can they get past an army of trolls, rescue Runner Bean and Charlie's ancestors, and get out before it's too late, or will Count Harken finally succeed?