Little Liar by Professor Julia Gray

Shortlisted for CrimeFest Best Crime Novel for Young Adults 2019.

Nora has lied about many things. But has she told her most dangerous lie of all?

There's a new art assistant at Nora's school, and he's crossed a line. Nora decides to teach him a lesson he won't forget.
But not everything goes quite to plan, and Nora needs an escape. She befriends the rich and talented Bel, who longs for a part in a remake of a famous film. Bel is unpredictable, jealous and crazy, but she opens up a new world for Nora, and that makes her irresistible.
As events start to spin wildly out of control, Nora must decide where her loyalties lie - and what deceits she can get away with.