The Horcrux Hunt
Harry Potter and the Half-Blood PrinceHarry and Dumbledore embark on a dangerous journey to retrieve a Horcrux from a cave, leading to Dumbledore's weakening and the discovery of the fake locket.
increasing
Bearing strength in each event
decreasing
First Private Lesson

The Beginning of the Secret Lessons
Setting the Stage
Albus Dumbledore begins private lessons with Harry Potter, revealing the importance of understanding Lord Voldemort's past. Using the Pensieve, they explore memories of Tom Riddle's early life, including the orphanage and the Gaunt family. Dumbledore emphasizes that the key to defeating Voldemort lies in knowing his history.
The First Glimpse of the Enemy
Harry witnesses the young Tom Riddle's manipulative nature and his ability to speak Parseltongue. These lessons are not just about history; they are a preparation for the final confrontation. Dumbledore hints that the ultimate goal is to find and destroy the Horcruxes, pieces of Voldemort's soul hidden in magical objects.
Building Trust and Knowledge
Harry feels honored to be chosen for these private sessions, but also burdened by the weight of the knowledge. The lessons strengthen his bond with Dumbledore, as they share a common purpose. However, Harry begins to notice Dumbledore's physical decline, symbolized by his blackened hand, foreshadowing the sacrifice to come.
The Memory of Slughorn

The Crucial Memory
The Task Assigned
Dumbledore tasks Harry with obtaining a memory from Horace Slughorn that Voldemort had tampered with. The memory involves a conversation about Horcruxes, where a young Tom Riddle asked about creating multiple Horcruxes. Dumbledore believes this memory is the key to understanding Voldemort's immortality.
Harry's Struggle
Harry attempts to persuade Slughorn, but the Potions master is evasive and ashamed. Using Felix Felicis, the luck potion, Harry orchestrates a meeting during Hagrid's burial of Aragog. He appeals to Slughorn's guilt and his admiration for Lily Potter, finally extracting the true memory.
The Revelation
In the memory, Slughorn reveals that a Horcrux is created by committing murder and that Voldemort was interested in making multiple Horcruxes, believing seven to be the most powerful number. This confirms Dumbledore's theory that Voldemort has created six Horcruxes, leaving his soul fragmented.
The Cave Expedition

The Descent into Darkness
The Journey to the Cave
Harry and Dumbledore Apparate to a remote sea cave, where Voldemort as a boy once terrorized other orphans. Dumbledore deduces that a Horcrux is hidden there. They enter through a fissure in the cliff, swimming through icy water into a cavern with a vast black lake.
The Potion of Despair
On a small island in the lake, they find a basin filled with a green potion. Dumbledore determines that the potion must be drunk to reveal the Horcrux. He forces himself to drink it, experiencing agonizing visions of past regrets and pleas for mercy. Harry, sworn to obey, forces Dumbledore to continue drinking, causing him immense suffering.
The False Locket
After Dumbledore drains the basin, they find a locket. But as they attempt to escape, Inferi rise from the lake. Dumbledore's fire spell protects them. Back at Hogwarts, Dumbledore is weak and is killed by Severus Snape on the Astronomy Tower. Later, Harry discovers the locket is a fake, containing a note from R.A.B. who stole the real Horcrux.
early October, after the start of term
late December, during the Christmas holidays
mid-June, the night of Dumbledore's death