Harry gets back to Hogwarts in the middle of a flurry of violent and deadly attacks on wizards and witches by You-Know-Who. Apparently, his strength is growing and his Death Eater followers are gathering again. Draco Malfoy's father is in Azkaban, so his mother visits Severus Snape to ask him to watch over Draco. Meanwhile, Harry and his posse see Draco making a visit to a disreputable magic items store and this convinces Harry that Draco has become a Death Eater. Later, once school starts, Harry is given an old copy of a potions textbook that was once owned by "the Half-Blood Prince," who was apparently very gifted in the art of making potions and wrote copious notes in his book. Because of this, Harry gets unusually high marks in his potions class, irritating Hermione. Later, Dumbledore enlists Harry to help him find out about some things called "Horcruxes". And in the midst of all this, the young heroes are falling in and out of love!! And I though MY high school years were tough!
This is my second favorite of the Harry Potter books (Deathly Hallows is the best)! It was fascinating in that we get to find out about Voldemort's past. Reading about the kids having crushes and fights made them even more realistic. And there were some really good fight scenes with actual mortal peril! The ending did such a good job setting up the story for the next book that this was the first HP book where I really COULDN'T WAIT for the next one!! I HIGHLY recommend this to HP and fantasy fans everywhere!
Read an extended description in my "What I'm Reading Now" article.