With less than a month to go until Harry Potter and the Half-Blood Prince hits UK cinemas, Newsround's been chatting to stars of the film, like Tom Felton who plays Draco Malfoy.
A touring trailer packed with memorabilia from the Potter films stopped in London for a few days and Tom, Matthew Lewis and James and Oliver Phelps all stopped by to check it out.
As hundreds of fans gathered to try to catch a glimpse of the boys, we took the chance to quiz them about what to expect in the Half-Blood Prince.
James and Oliver told us they had the best set to work on during filming as their characters, Fred and George Weasley, have finally opened their own joke shop.
But as well as seeing them fulfil their mischievous dreams, Oliver said: "You also see an undercurrent with how the dark world is catching up with all the Weasley family and Harry."
Talking of the dark side... Tom said Draco Malfoy is a lot meaner in the Half-Blood Prince. "He definitely steps it up a gear this year," he said. "He gets a bit more physical."
Tom and Matthew were happy to pose together with fans for photos, but you're unlikely to catch their characters, Draco and Neville Longbottom, doing the same thing in the film.
Matthew reckons Neville's changed a lot over the past six films and says he's a lot stronger-willed in the Half-Blood Prince.
"He started off as a very shy, vulnerable student who got bullied a lot and then with Harry's help he's come through as a great wizard," he said.
When we caught up with the Potter stars it was just a few hours after they'd seen the final cut of the Half-Blood Prince for the very first time. So what did they think of it...?
"Word's can't describe how good it was to me," said Tom. "It blew my expectations out of the water."
Matthew reckons it's "a rollercoaster ride" with something for everyone. "Look out for Jim Broadbent as Professor Slughorn," he said. "He's so good and people are going to love him."