In the Order of the Phoenix. At the end of this movie, Harry to know about a terrible secret- he across a prophecy made about Harry n Voldemort n the reason y Voldemort wanted to kill him as a baby. The prophecy says that the boy with the power to vanquish the dark lord shall b born at the end of july(harrys birthday) will have powers the dark lord knows not n the dark shall mark him as his equal n neither can live while the other survives.