In the third installment, Harry Potter and the Prisoner of Azkaban, Watson returns as Hermione Granger, helping Harry, Ron, and Professor Remus Lupin (David Thewlis) find Sirius Black, an escaped serial killer, while uncovering the mysteries surrounding the night Harry became an orphan.
Oh, I loved it! It’s my favorite book, my favorite script, and it’s such a fantastic part for Hermoine. She really comes into her own, and I think you see a really different side to her than you have in the other two [films]. I think it’s much more personal, and this film has really tested and challenged me, and I’ve definitely enjoyed it the best out of the three because of that … I hope that I did her justice and that she’s what (fans) thought she’d be.