Harry, Ron and Hermione race against time to destroy the remaining Horcruxes. Meanwhile, the students and teachers unite to defend Hogwarts against Lord Voldemort and the Death Eaters.

After Voldemort takes over the Ministry of Magic, Harry, Ron and Hermione are forced into hiding. They try to decipher the clues left to them by Dumbledore to find and destroy Voldemort’s Horcruxes.

Dumbledore and Harry Potter learn more about Voldemort’s past and his rise to power. Meanwhile, Harry stumbles upon an old potions textbook belonging to a person calling himself the Half-Blood Prince.

Harry Potter and Dumbledore’s warning about the return of Lord Voldemort is not heeded by the wizard authorities who, in turn, look to undermine Dumbledore’s authority at Hogwarts and discredit Harry.

When Harry is chosen as a fourth participant of the inter-school Triwizard Tournament, he is unwittingly pulled into a dark conspiracy that endangers his life.

Harry, Ron and Hermoine return to Hogwarts just as they learn about Sirius Black and his plans to kill Harry. However, when Harry runs into him, he learns that the truth is far from reality.

A house-elf warns Harry against returning to Hogwarts, but he decides to ignore it. When students and creatures at the school begin to get petrified, Harry finds himself surrounded in mystery.