Leo Castenada is Spanish and lives in Brussels. He is a metro driver for line 6. One night, he sees a stranger at the edge of the platform. With eyes full of anxiety and a familiar face, Leo recognised his son Hugo just as he tragically jumps onto the rails. Leo, who had not seen his son for more than two years, discovers that Hugo was involved in a violent robbery. Leo is forced to confront violent criminals in order to try and understand why his son took his own life.