Two Truths and a Lie by Sara Shepard

Emma Paxton thought she’d finally found her twin sister Sutton after years in foster care — only to discover Sutton is dead, and someone is pretending to be her. Forced to take her sister’s place in a life of luxury, secrets, and lies, Emma must play along to stay alive while searching for the killer hiding among Sutton’s friends. But as she digs deeper into her twin’s glittering world of deceit, Emma realizes that everyone around her has something to hide — and one wrong move could make her the next victim in the deadly game Sutton left behind.