The 4th book and yet again full marks. 
 The Goblet of Fire marks a turning point in the series: Things get Serious. Bad things happen and not even magic can make all things right again. The beginning of the novel fiends Harry again at the Dursleys, but things change a for the better when Ron and his family invite him over for the summer to see the Quidditch world cup. And that fact alone makes the biggest biggest expansion in the series so far. There is more than just Hogwarts, England and the wizards who live there. There is a whole world of magic out there to see and explore and in HP4 we get to see part of it. 
 A truly wonderful novel and an absolute joy to reread.