J K Rowling's writing and story telling are at their finest in the fourth Harry Potter book. She weaves all the plot elements together very skillfully. I loved her first four books because, at their heart, they were tales of mystery and adventure and this one was the best of them. After this one, the series went into a different direction, one more concerned with telling the history of Voldemort and Harry and bringing the tale to it's conclusion. This book remains Rowling's best.