Here is the fourth installment in our synopsis of Harry Potter and the Half-Blood Prince, the sixth book in the series — your essential cheat-sheet for diving into the seventh and final book, Harry Potter and the Deathly Hallows. See chapters 1-5 summarized here, 6-10 summarized here, and 11-15 summarized here.
Chapter 16 - A Very Frosty Christmas
Harry is spending Christmas at the Burrow with the Weasleys. He fills Ron in on the argument he heard between Snape and Malfoy and mentions the unbreakable vow Snape made. It can't be denied that Malfoy is up to something, but Ron says everyone thinks that Snape is trying to figure out what Malfoy is doing rather than really offering him help. Harry discusses the matter with Mr. Weasley. He definitely does not trust Snape, but Mr. Weasley and Lupin trust Dumbledore and Dumbledore trusts Snape. Lupin reveals that he's been hanging out with the werewolves, which proves to be difficult since Lupin does not share the (rather bloody) werewolf lifestyle. Voldemort's biggest werewolf advocate, Fenrir Greyback, the most savage of them all, has made a good case for the werewolves to join Voldemort. Greyback is also the werewolf who bit Lupin when he was a boy. Harry asks Lupin if he knows who the Half-Blood Prince is, but Lupin has no idea and suggests that Harry start by looking at when the his potions book was published to figure out who might have owned it (about 50 years ago). Harry and Ron wake up Christmas morning to a couple nice gifts (hand-knit sweaters from Mrs. Weasley) and some nauseating ones (a "My Sweetheart" necklace from Lavender to Ron and a package full of maggots from Kreacher to Harry). Over Christmas lunch, Rufus Scrimgeour, the Minister of Magic, and Percy, who is still on bad terms with his family, stop by the Burrow for an awkward visit. Scrimgeour has used Percy as an excuse to visit with Harry. Scrimgeour and Harry walk out to the yard to talk. Scrimgeour wants Harry to tell him what Dumbledore is up to (specifically the trips that he's been taking) and if Harry would work with the Ministry to help improve morale and give people a sense of security. Harry refuses both requests, proving himself to be loyal to Dumbledore and not to the Ministry. He leaves Scrimgeour in the yard.
Chapter 17 - A Sluggish Memory
Harry, Ron and Ginny return to Hogwarts after Christmas vacation via Floo network. They are greeted by Hermione, but she is still not on speaking terms with Ron. She gives Harry a message from Dumbledore about their next lesson. Harry fills Hermione in on the Snape-Malfoy conversation. Like the others, she is skeptical of Harry's theory that Snape is not trustworthy. They wake up the next morning to find out that they are eligible to take Apparition lessons, which becomes the all-consuming topic of conversation for the rest of the day. Harry goes to Dumbledore's office for his lesson and notices that the headmaster's hand is still black and dead-looking as ever. They discuss Scrimgeour's visit to the Burrow and Harry tells Dumbledore that he is loyal to him and not the Ministry. Dumbledore is touched. Harry tells Dumbledore about Snape and Malfoy, but Dumbledore reassures Harry that Snape is trustworthy and does not want to discuss the matter further. Harry still isn't convinced and is rather annoyed that Dumbledore does not side with him. They commence their pensieve lesson.
Dumbledore recaps what had happened when Voldemort (Tom Riddle) arrived at Hogwarts. The Sorting Hat immediately places Tom in Slytherin and he eventually figures out that the founder of the house was also a Parseltongue, a fact that probably boosted Tom's self-importance. Despite Tom's disturbing behavior at the orphanage, Dumbledore decides to give him a chance and hopes that Tom will turn a new leaf. Tom became a quiet, polite kid, who manages to win over students and professors alike. The popular Tom gains a following at Hogwarts that later became the Death Eaters. Tom grows obsessed with parentage, but eventually comes to realize that his father never attended Hogwarts. He then begins searching his mother's lineage using his middle name Marvolo, which eventually yields some results. He discovers both the Slytherin line and the Gaunt family.
Harry and Dumbledore enter the pensieve and they arrive back at the old run-down house the Gaunts occupied. Tom enters that house to find Morfin there alone, and they figure out that they can each speak Parseltongue. Morfin, who is wearing Marvolo's black stone ring, tells Tom that Marvolo is dead. He also tells Tom that he looks like the muggle up the road who Merope had taken a fancy too. Morfin tells Tom that Merope had run away and taken the family locket with her. Tom Sr. had returned to town and abandoned Merope. Voldemort approaches Morfin and the lights go out. Harry and Dumbledore exit the pensieve. Dumbledore tells Harry that Voldemort stole Morfin's wand, killed Tom Riddle Sr. and his parents, stole the black stone ring, and placed a false memory in Morfin's head making Morfin confess to the murder of the three muggles. Dumbledore tried to prove Morfin's innocence but by that time Morfin had passed away.
They enter the pensieve again. This time they enter the study of Slughorn where there sits a group of boys, Tom among them. All the boys admire Tom as Slughorn pays him compliments. The memory suddenly gets cloudy and Slughorn's voice sounds unnaturally loud as he says: "You'll go wrong, boy, mark my words." The memory clears up again and Slughorn is hurrying everyone off to bed. Tom hangs back and when they are alone, he ask Slughorn about Horcruxes. The memory gets cloudy again and Slughorn's loud voice says that he knows nothing of Horcruxes and Tom shouldn't ask about them again. The memory ends. Dumbledore tells Harry that the fog was a sign that the memory had been tampered with. He gives Harry the task of figuring out what really happened during those foggy moments by coaxing it out of Slughorn. Harry is dismissed.
Chapter 18 - Birthday Surprises
Harry tells Hermione and Ron (who still are not on speaking terms) about the task Dumbledore gave him. He also asks Hermione if she knows anything about Horcruxes. She doesn't, though she suspects they are some sort of advanced dark magic. Harry wonders what his plan of action should be. They are in Potions class when Slughorn sets everyone to the task of finding antidotes for potions they have randomly selected. Hermione brightly tells Harry that the Half-Blood Prince probably can't help him with this assignment. Not sure what to do, Harry randomly tries the spells his fellow classmates are using until he reads a scribble in his text that says, "Just shove a bezoar down their throats." Harry remembers from his first day in Potions that a bezoar can protect someone from most poisons. He grabs a bezoar off the shelf just when time is up. Slughorn walks around looking at everyone's antidotes and when he gets to Harry, Harry shows him the bezoar. Slughorn is delighted and calls Harry rather gutsy for using a bezoar for his antidote. Hermione, of course, is very unhappy. Harry hangs around after class and when he and Slughorn are alone, he asks Slughorn about Horcruxes. Slughorn immediately picks up on Harry's intentions, and storms out of the classroom. Although Slughorn is still affectionate to Harry, he does not extend the expected dinner invitations to Harry. Hermione can't find a thing about Horcruxes, only that they are the "wickedest of magical inventions." Wilkie Twycross of the Ministry shows up to teach everyone how to Apparate, which turns out to be extremely difficult. During the lesson Harry tries to listen in on a conversation between Malfoy and his two goons Crabbe and Goyle and picks up that Malfoy is planning something. Everyone starts to practice Apparating and Susan Bones manages to splinch (separation of random body parts in the process of Apparating) herself. After Apparition practice, Harry comes up with the idea to use the Marauder's Map figure out what Malfoy is doing. Should Harry see Malfoy in a suspicious place, he can then use his invisibility cloak to see what Malfoy is up to.
The next day is Ron's birthday. While Ron opens presents and stuffs his face with chocolate cauldrons, Harry tries to find Malfoy on his Marauder's map, to no avail. On their way to breakfast, Ron starts acting strangely. Ron says he's desperately in love with Romilda Vane. Harry thinks it's a joke till he sees the chocolate cauldron that Ron had eaten: they were the ones Romilda had been pushing on him which were filled with love potion. Harry tricks Ron into going to Slughorn's quarters with him to get an antidote for the love potion. Slughorn gives Ron something to drink and he suddenly becomes very depressed looking (a sign that he's cured). Slughorn shares an oak-matured mead he had meant to give to Dumbledore for Christmas to give Ron a pick-me-up. Ron downs the entire cup and starts to jerk uncontrollably. Harry quickly finds a bezoar and shoves it in Ron's mouth. Ron gives a shudder and becomes still -- alive, but not well.
Chapter 19 - Elf Tails
Ron lays recovering in the hospital wing while Harry, Hermione, George, Fred and Ginny speculate as to what happened. There seems to be no reason for Slughorn to want to poison Ron. Ginny reasons that the mead was poisoned because it was meant for Dumbledore. Hermione, Harry and Hagrid leave Ron to the Weasley's care and visit with Hagrid. Hagrid accidentally mentions that Dumbledore and Snape had an argument. Snape had looked stressed and overworked and Dumbledore insisted that Snape had agreed to do something. Meantime Harry, who is still obsessed with finding out what Malfoy is up to, finds Malfoy with two girls and demands to know what Malfoy is doing. Malfoy tells him to mind his own business and Harry rushes off to the Gryffindor Quidditch match against Hufflepuff. During the match, McLaggen, who is filling in for Ron, is bossy and difficult. Harry tries to intervene and McLaggen ends up smacking him in the head with a Bludger that he had hit using the bat he stole from his teammate. Harry wakes up in the hospital with a newly-healed cracked skull. Harry and Ron discuss the latest Malfoy incident and Harry comes up with an idea. He calls on Kreacher who has been working with the other elves at Hogwarts. Kreacher apparates to the hospital wing, but Dobby is there too, beating Kreacher up, as he will not hear anyone talk badly of Harry and Kreacher tends to speak badly of Harry all the time. Harry gives Kreacher the task of following Malfoy around and giving reports as to what Malfoy is doing. Dobby also volunteers to do the same. Harry warns Kreacher not to tell anyone.
Chapter 20 - Lord Voldemort's Request
Harry and Ron leave the hospital wing and to Harry's delight he finds out the Ginny and Dean are in a row. Hermione and Ron have also become friends again after his recovery. Harry gets another note from Dumbledore about their next meeting. When he goes to Dumbledore's office, Dumbledore asks if he's made any progress obtaining Slughorn's memory. Harry feels guilty because between everything that his happened and his obsessive efforts trying to figure out what Malfoy is up to, Harry has barely put in any time with Slughorn. He promises Dumbledore he will try harder. Before they jump into the pensieve Dumbledore provides Harry with a little background. As a seventh-year student, people expected great things of Tom after school ends, but he ended up working at Borgin and Burkes, a disappointment to many. But before he went to Borgin and Burkes, Tom had asked the headmaster at the time, Professor Dippet, for a teaching position, probably because 1) Hogwarts was the first place he actually felt at home, 2) Hogwarts castle is a stronghold of ancient magic, which Tom had already experienced (Chamber of Secrets), and 3) as a teacher he would have great influence over all the young witches and wizards he would teach. Dippet declined and said Tom was too young and should reapply in the future. So Tom began working with Borgin and Burkes where he held the very particular job of acquiring unusual, powerful objects.
Harry and Dumbledore dive into the memory of a house-elf named Hokey who belonged to a very rich witch named Hepzibah Smith. They see Hepzibah frantically trying to get ready for the arrival of Tom Riddle whom she obviously has a huge crush on. She decides to show Riddle two very valuable possessions she doesn't want to sell and hasn't shown Burke; Hokey fetches them for her. One is a small golden cup with two handles and a badger symbol that belonged to Helga Hufflepuff. Tom looks greedily at the cup knowing that it is very powerful. Hepzibah puts it away and shows him the second item. It is the Slytherin locket that once belonged to Merope, which she had purchased from Burke a while back. Tom holds it, and is hesitant to give it back, but does. Hepzibah looks a little unnerved and tells Hokey to lock the items up again. Harry and Dumbledore exit the memory. Dumbledore tells Harry that a few days later Hokey was convicted of accidentally poisoning Hepzibah's cocoa. Voldemort had modified Hokey's mind to make her think that she poisoned her mistress. Hepzibah's family realized the cup and locket had gone missing, but by that time Tom had resigned from Borgin and Burkes and disappeared not to be seen for a very long time. Dumbledore points out that Tom had killed this time not for revenge (like he killed Tom Riddle Sr.) but rather for personal gain. He also notes that Voldemort felt entitled to the locket and drawn to the cup because of its link to Hogwarts.
Next they enter a memory of Dumbledore's. Tom pays a visit to Dumbledore. He is no longer the handsome man he was before, but rather scary looking. Dumbledore still calls him Tom, though the young wizard asks to be called Voldemort. Voldemort has come back to ask for a teaching position at Hogwarts. Dumbledore notes that there are rumors about terrible things that Voldemort has done, but Voldemort claims that they are just lies spawned from jealousy. Dumbledore doubts this however, and says that although he knows Voldemort is very skilled in magic, he also remains ignorant. Voldemort tells Dumbledore that he has yet to see how love is more powerful than magic and says that Hogwarts might be the place where he can explore this. Dumbledore speaks frankly and says that he will not give Voldemort a job and asks to know his real reason for returning to Hogwarts. Voldemort says since Dumbledore will not help him he has nothing left to say and leaves. Harry asks Dumbledore why Voldemort wanted the job and Dumbledore says he doesn't know but can figure it out when Harry gets Slughorn's memory. Dumbledore also reveals that ever since that night, Hogwarts has not been able to retain a Defense Against the Dark Arts professor for more than a year since refusing the post to Voldemort.
Chapter Recaps: 1 -5 [HuffPo]
Chapter Recaps: 6 - 10 [HuffPo]
Chapter Recaps: 11-15 [HuffPo]
Related:
Harry Potter: The Cheat Sheet [HP on HP]