In the 1960s, António, an agent of the PIDE, is assigned to follow Aurora to Paris, a young woman suspected of oppositionism. It is May 1968, and during the student revolt, the two young people fall in love. Back in Porto, their forbidden passion ends abruptly. For decades, António writes Aurora letters that she keeps unopened. When the correspondence is unexpectedly interrupted, both give up on life. Based on the director's novel entitled "A Casa Azul" (The Blue House).