«El director cree que no es conveniente que eso continúe ocurriendo. Quiere que te enseñe a cerrar tu mente al Señor Tenebroso.» Son malos tiempos para Hogwarts. Tras el ataque de los dementores a su primo Dudley, Harry Potter comprende que Voldemort no se detendrá ante nada para encontrarlo. Muchos niegan que el Señor Tenebroso haya regresado, pero Harry no está solo: una orden secreta se  reúne en Grimmauld Place para luchar contra las fuerzas oscuras. Harry debe permitir que el profesor Snape le enseñe a protegerse de las brutales incursiones de Voldemort en su mente. Pero éstas son cada vez más potentes, y a Harry se le está agotando el tiempo... “The Headmaster believes that it is not wise for you to continue to do this. He wants me to teach you how to close your mind to the Dark Lord.” Dark times are coming to Hogwarts. Following the Dementors' attack on his cousin Dudley, Harry realizes that Voldemort will stop at nothing to find him. Many deny that the Dark Lord has returned, but Harry is not alone: a secret order meets at Grimmauld Place to fight the dark forces. Harry must allow Professor Snape to teach him how to protect himself from Voldemort's brutal attacks on his mind. But these are getting more and more powerful, and Harry's time is running out.