In the start of Harry's 6th Year, he gets a mysterious letter signed by 'Snuffles'. After confirming that it was, indeed from none other than his godfather Sirius Black, Harry's excitement could barely be contained.

He sent letters to Albus Dumbledore and his old professor, Remus Lupin, both of who seemed skeptical, of course, but eventually were convinced the letter was indeed written by Sirius Black.

Around the same time, Remus Lupin returns to Hogwarts to teach another year of Defense Against the Dark Arts. This class needs a good instructor now more than ever, as the likelihood of an all-out war with Lord You-Know-Who draws nearer.

Voldemort's power gets stronger and stronger every day, and he has begun recruiting more and more followers, some of them young students at Hogwarts.

Harry, Hermione and Ron have decided to start up Dumbledore's Army again, and are looking for new members. Only the Golden Trio know the true meaning for the DA this time around: to prepare for an all-out attack against You-Know-Who.