The Mirror And The Mountain PB by Luke Aylen

When Jonah and Summer stumble upon a secret passage and discover an enchanted mirror, they unwittingly begin an adventure that will take them far from their home into the magical kingdom of Presadia
 
Trapped in a war-torn kingdom with no way home, Summer and Jonah are pulled into a strange quest to find the long-lost king, who alone has the power to restore peace to Presadia. 
 
Meeting strange and wonderful people along the way, including the dwarf high lord, the elf queen and a fire-breathing dragon, they learn important lessons about pride, greed, and the power of words as they embark on an epic journey to save the realm.
 
The children and their new friends must be brave as they fly across the broken kingdom and climb a misty mountain. Can they fulfil their quest to find the king and restore peace to Presadia? And will Summer and Jonah ever make it back to their own world?