In "Harry Potter and the Order of the Phoenix," the fifth book in the series by J.K. Rowling, Harry Potter returns to Hogwarts School of Witchcraft and Wizardry for his fifth year. He faces challenges from the oppressive new Defense Against the Dark Arts teacher, Dolores Umbridge, who enforces strict rules and punishes students. Meanwhile, Harry struggles with the return of Lord Voldemort and the growing threat to the wizarding world. To combat this darkness, Harry joins the Order of the Phoenix, a secret group formed to fight against Voldemort and his followers, the Death Eaters. Alongside his friends, Hermione Granger and Ron Weasley, Harry learns about the importance of friendship, loyalty, and standing up against tyranny. The story explores themes of resistance and the power of unity in the face of adversity.