Üniversitede tarih dersleri veren Adam, okul ve ev arasında gidip gelen monoton hayatına en azından bir kız arkadaş sığdırmayı başarmıştır. Bir gün bir arkadaşının tavsiyesi üzerine bir film izler ve o filmde kendisine çok benzeyen birisini görerek, bu oyuncunun peşine düşer. Adam artık, kendisine ikizi kadar benzeyen Anthony'nin de hayatının bir parçasıdır, tabii Anthony de onunkinin.
Yönetmenliğini Denis Villeneuve'nin üstlendiği gerilim filminin senaryosunu ünlü yazar José Saramago'nun romanından uyarlayan isim ise Javier Gullón. Kadroda Jake Gyllenhaal, Mélanie Laurent ve Sarah Gadon gibi isimler yer alıyor.
Adam Bell is a Toronto area History college professor. He is a rather somber man, largely because he is stuck in a routine, which includes a relationship with his live-in girlfriend, Mary. While watching a rental movie, he spots an actor in a bit part that looks like him. He becomes obsessed with finding out about this double of his. He learns that the actor's stage name is Daniel Saint Claire, whose legal name is Anthony Claire. Claire is a Toronto based actor with only a few on-screen credits, and is married to a woman named Helen who is currently several months pregnant. Adam then becomes obsessed with meeting Claire, who he learns upon first sighting that they look exactly the same, from the facial hair to a scar each has, but Claire who outwardly is more "put together" than Adam. Their lives become intertwined as Claire himself ends up becoming obsessed with Adam, but in a slightly different way.