They're Watching You by Chelsea Ichaso

When a secret society has you in their sights, it can lead to power, privilege or death.It's been two weeks since Polly St. James went missing. The police, the headmistress of Torrey-Wells Academy, and even her parents have ruled her a runaway. But not Maren, her best friend and roommate. She knows Polly had a secret that she was about to share with Maren before she disappeared something to do with the elite, ultra-rich crowd at Torrey-Wells.Then Maren finds an envelope hidden among Polly's things an invitation to the Gamemaster's Society. Do not tell anyone, it says. Maren is certain her classmates in the Society know the truth about what happened to Polly, though it's no easy feat to join. Once Maren's made it through the treacherous initiation, she discovers a world she never knew existed within her school, where Society members compete in high-stakes games for unheard-of rewardsIvy League connections, privileges, favors.But Maren's been drawn into a different game for every win, she'll receive a clue about Polly. And as Maren keeps winning, she begins to see just how powerful the Society's game isbigger and deadlier than she ever imagined. They see, they know, they control. And they kill.