A Goodreads user asked:
How old are the two main characters in this?
Jonathan Friesen I know! Okay, Clara has finished school in London, and Elias has been held back many times. This makes both of them older, 18 and 19.
Courtney Briee Elias is 19, however Clara's age is never stated throughout the book. She could be anywhere from 16-22ish.