Spoilers for the earlier ones ahead!
Harry manages a nicer summer by frequent allusions to writing to his godfather, who might get angry with the Dursleys. And this one snatches Harry away sooner, off to the Quadditch World Cup with the Weasleys. Much fun and games with the wizarding world, until a Death Mark appears, warning of one of the Lord Voldemort's Death Eater minions.
Then they are off to school again. Where they hear of a new competition, the revival of the Triwizard Tournament, with measures taken to decrease its lethality, and limits to ages, as over seventeen. And students from two other schools arrive, because there will be a champion from each. Except that when the title cup spits out the names of the champions, it does four. And one is Harry. And a good number of people don't believe that he didn't put it in.
It involves Ron's brother Charlie bringing dragons to Hogwarts, learning about curses early, the lake, presents of socks, dealing with the other Hogwarts champion Cedric Diggory, the Yule Ball, which Harry needs a date for, an obnoxious reporter, and more. Like Prisoner, had serious consequences. Indeed, some are higher than in Prisoner. (still like Prisoner better.)
One thing had a new edge, re-reading:[Spoiler (click to open)]Amos Diggory talking about how Cedric beat Harry at Quadditch -- he'll be able to tell his grandkids that. (Bit steep a punishment there.)
And a couple of things bugged me:
[Spoiler (click to open)]Why all the pother of a tournament? Why not just have "Moody" slip Harry a Portakey? All the sharper in that it could have been fixed easily. The spell requires the enemy used to have been tested and triumphed, perhaps. Or for some reason, it will make the enemy's blood all the more powerful. Or even that Voldemort thinks that snatching the champion at the moment of triumph will make the wizards all the more afraid of him; he's certainly willing to sacrifice much for that.
And one's realy a series inconsistency. I can not believe that they didn't wring every follower they caught dry with Veritaserum. Failing that, they could have slapped the Imperius curse on them and decreed: Tell the truth. Mind you, that would have overturned the whole plot, but then using it here is a weakness.