Alex Walker has always looked up to her perfect older sister. Maddie escaped their hometown and seems to have put the memories of their unstable childhood behind her. But despite the different paths their lives have taken, they made a pact to spend one week together every summer. It was a promise they’d never broken...until now. When Maddie suddenly cancels her annual trip home, Alex begins to worry. But when Maddie stops returning her calls altogether, Alex is certain something is wrong. Relying on the only clues Maddie left behind, Alex follows her sister’s footsteps to the Hamptons where she meets the Blackwell family --- the last people to have seen Maddie before she vanished into thin air. The Blackwells seem to have it all, but Alex quickly discovers that a life of luxury always comes at a cost.