The Lying Game (2011)

Emma, a resilient foster child, discovers she has an identical twin, Sutton, who enjoys a privileged life with her adoptive family. Eager to help Sutton track down their birth mother, Emma agrees to temporarily assume her sister’s identity. However, excitement quickly turns to dread when Sutton disappears under mysterious circumstances. Faced with the dilemma of revealing her true identity to Sutton’s affluent family, Emma grapples with the risks involved while racing against time to uncover the secrets surrounding their separation and her sister's fate.