Changeling (2008)

Los Angeles, 1928: On a Saturday morning in a working-class suburb, Christine (Angelina Jolie) said goodbye to her son, Walter, and left for work. When she came home, she discovered he had vanished. A fruitless search ensues, and months later, a boy claiming to be the nine-year-old is returned. Dazed by the swirl of cops, reporters and her conflicted emotions, Christine allows him to stay overnight. But in her heart, she knows he is not Walter.