Harry Potter and the Half-Blood Prince by J.K. Rowling

The end is near...

Harry Potter and his friends Ron and Hermione are up to their necks in trouble. The world is falling apart around them as the wizarding world struggles to maintain a calm front in the face of impending war. While the book may advertise itself as year 6 at Hogwarts, school is no longer the focus for Harry. He's more concerned with an imminent attack by the evil Death Eaters, and remains busy trying to convince anyone who'll listen that Draco Malfoy is plotting something awful. Dumbledore shows a great deal more confidence in Harry, and begins a series of private lessons to see if they can unravel the riddle of...well...Tom Riddle (aka you-know-who). Lessons, and even Quidditch, take a backseat to mystery and war. Harry is trying to determine what exactly has happened to Dumbledore during the summer, as his greatest teacher appears to have lost a few battles. Professor Snape is getting viler by the moment, looking for any excuse to get at Harry. To make matters worse, Snape has made an unbreakable vow to protect Draco Malfoy at all costs. But all may not be as it seems. As wizard-on-wizard crime increases and war draws near, Hogwarts seems to be falling apart at the seams. As Harry's quest with Dumbledore draws to a close, Hogwarts becomes the staging ground for the beginning of the final conflict. Harry suffers an unimaginable loss, an incredible betrayal, and through it all, manages to fall in love.

Some of Rowling's plot points feel stiff and predictable, but these shortcomings can be overlooked when a story is this good and this much fun.