What is the theme of Harry Potter and the Goblet of Fire?

Well the theme of all the Harry Potter books is MAGIC. But in Goblet of Fire, the Tri-wizard tournament and return of the Dark Lord- Lord Voldemort are very important. book one: the discovery of wizrds witchs magic and stuff. book two:mysteries. going deeper into voldemort and harry potter connections book three: more of harry potters parents and how they were murdered. book four:facing the corruption of the ministry of magic. and going way deeper into voldemort and harry potter connections. book five:discoverying alot about the plans of voldemort. book six:love :P and learning alot and i mean ALOT about voldemort. book seven:the final challenge. summarizing and answering millions of details over the past books.