Half-Blood Prince..

The war against Voldemort has started, and everyone in the wizarding world has chosen sides. (They have to, or else a side will choose them.) Even in the midst of a war, your daily life goes on — captaining the Quidditch team, studying Transfiguration and Potions, dreaming of that beautiful redhead in the fifth year. And yet everything is about to change . . .

After five years of thrills and adventure, Harry Potter’s life is taking a new path — straight to a fight against Lord Voldemort. But first he and Professor Dumbledore must try to find out as much as they can about a boy once named Tom Riddle — the boy who became Lord Voldemort. Discover the history that will determine the future — read Harry Potter and the Half-Blood Prince.

The sixth book in the series, Harry Potter and the Half-Blood Prince, was published in the UK, US and other English-speaking countries on 16th July 2005 and also achieved record sales.