The Five Kingdoms - The Pegasi Chronicles Book 3

Eleven-year-old Jason and his companions barely escape with their lives. However, their flight launches them through an interdimensional portal into another world, the World of the Five Kingdoms. It's the world his father came from, but it's also the world of the Rewera, a race of immortals whose goal is to destroy humanity. It's also a world devoid of internet, television, and cell phones, a world that eerily resembles Victorian England.
Jason discovers that he is a member of a royal family, a prince in the Kingdom of Pegasus. He soon learns, however, that privilege comes at a price. Rebelling against the constraints and expectations of his newly discovered royal family, he flees the palace along with a page boy and a new friend, Ari. What was supposed to be an afternoon of freedom from responsibly ends up with the three boys imprisoned and sentenced to a juvenile chain gang.
No one realizes that Jason is a member of the royal family. It's now a race to see who can find the missing prince first: his Uncle Richard or the Rewera. The influence of evil is growing in both this new world and Jason's home world. According to legend, Jason has the power to stop the evil that is spreading in both worlds; it's his destiny. Only thing is, the legend suggests that there is only one way he can fulfil his destiny.
He has to die.