The Kingdom Over the Sea by Zohra Nabi

My own Yara, if you are reading this, then something terrible has happened, and you are on your own.

To return to the city of Zehaira, you must read out the words on the back of this letter . . .

Good luck, my brave girl. When Yara's mother passes away, she leaves behind a letter and a strange set of instructions. Yara must travel from the home she has always known to a place that is not on any map - Zehaira, a world of sorcerers, alchemists and simmering magic.