In this episode, the Death Eaters begin to run rampant in both the Muggle and Magic worlds, and Hogwarts is in crisis. Dumbledore (Michael Gambon) takes Harry (Daniel Radcliffe) to find Horace Slughorn, who has been in seclusion for many years, and asks him to come out to replace Snape (Alan Rickman) as the teacher of Potions. Horace has taught countless outstanding students, and Tom Riddle - Voldemort - is his most outstanding disciple. Dumbledore is convinced that Horace has the secret of Voldemort's immortality, and he hopes that Harry can convince Horace. On the other hand, Draco Malfoy (Tom Felton) swears allegiance to Voldemort, and he tries every means to introduce Death Eaters to Hogwarts. At this time, Ron (Rupert Grint) and Hermione (Emma Watson) were still immersed in the agitation of youth, unaware that darkness was approaching...