Watch The Impostor Full Movie Free Online 123Movies. This drama is based on a novel and incomplete screenplay by the late Maria Luis Bemberg. In 1930s Argentina, wealthy Sebastian (Antonio Birabent) leaves his Buenos Aires home for the family estate on the pampas. His family, concerned for his physical and mental health, arranges for Sebastian's childhood friend Juan (Walter Quiroz) to check on Sebastian's situation. Juan finds the highly erratic Sebastian caught in a doomed relationship with the Danish daughter of religious sect members. Unfortunately, Juan also becomes obsessed with the young woman, and Sebastian's suspicions increase.