Harry Potter and the Curse of the Full Moon

Voldemort is back and about to kill Harry but decides to curse Harry he orders Greyback to bite Harry and turn him into a Werewolf, but when Harry returns to Hogwarts he learns that it's a full moon so with little time to spare he uses a time turner to get ready while staying out of the way of his friends, himself and most of all not changing anything that could alter the present.