Ada Howell had an idyllic childhood growing up in Garreg Las, the ancient country house of her adopted father. But when he dies, Ada's mother quickly sells up taking her daughter to live a far more modest life in London – a life so frightfully mediocre, Ada refuses to accept it as her own.
When Ada's eccentric godmother gifts her with an exclusive gap-year art history trip to Italy, Ada finally finds herself amongst the kind of people she aspires to be: sophisticated, cultured, privileged. Over the course of two dazzling months, Ada does everything in her power to prove she is one of them. But it is only when Mallory, the least popular member of the group, dies in suspicious circumstances that Ada spots an opportunity to permanently bind herself to the lives of her companions. To do so, she must help bury a secret, but everything hidden must eventually surfaces and when it does, Ada realises she's been keeping a far darker secret than she ever imagined.