"Before hopping on a plane to Santa Monica, I wish I would have known following three things:
One: It's going to be unbearably hot sometimes.
Two: Spying is hard work and only really works in the movies.
And three: Mason Jones will creep into your head. A lot."
When Jane is invited by her mother's friend Alison to spend her summer before college at her house in Santa Monica, L.A., it's all she can think about until she actually gets there and meets the boy who she'd forgotten existed: Mason Jones, Alison's son who used to be the shy boy who didn't want to play with her at visits. Ten years later, he's twenty, grown up, charming looking and ... still a tad rude.
While living in their house for two months, Jane quickly learns that Mason seems to be tangled in criminal affairs - which has his parents worry to the point they decide to ask Jane to spy on him.
While decently stalking Mason on her own and becoming more understanding and fond of him at the same time, Jane does not only unravel old dark secrets but also she finds out that there's someone out there who looks exactly like Mason, seeking to save him.