Harry Reveals Slughorn's Memory and News of the Mystery - Lord Voldemort's Horcruxes
Pages 513-514
Harry tells Ron Weasley and Hermione Granger about how he persuaded Horace Slughorn to give him the vital memory, detailing Tom Riddle's interest in Mystery - Lord Voldemort's Horcruxes. He explains how Albus Dumbledore plans to take him along if another Horcrux is found. Ron is impressed, while Hermione seems more focused on Ron's spellwork and accidental snowfall during class, which causes awkwardness with Lavender Brown.