If you liked Harry Potter, You'll love The Portal Keeper!
 
Young Ajax is tasked with guarding the mysterious kingdom's portal, a sacred duty passed down through his family and recently abandoned by his older brother, bringing shame to his family. Few outside the royal family even know of its existence and there is a mysterious prophecy warning of its danger.
When the prince of Rastella comes to visit the portal, disaster strikes! In an accident, the prince falls into the portal and Ajax knows that it's up to him to venture in and get him back. With the knowledge that nobody who has entered it has ever returned, Ajax and his childhood friend, Nivara leap through the portal to try to save the prince. They discover a world full of magic and fantastic creatures, in an adventure that will test them to their limits, and leave them wondering if they will ever get home.