Clare Youell reports for CBBC Newsround Online at the Prisoner of Azkaban DVD launch.
It's dark, it's raining, there's smoke rising from the pavements. Then, through the mist, a huge, purple, triple-decker bus appears.
This can only be the launch party of the latest Harry Potter DVD.
It is. And it's magical.
As the bus swings around to face the world's press, three faces appear from the back of the vehicle.
Dan, Rupert and Emma (Harry, Ron and Hermione) are ready to face the cameras. The three Potter pals looked relaxed and happy, and they chatted easily to each other like the good mates that they are.
Once the scrum is over, the rest of the cast saunter in. First up are the baddies - boo! Tom Felton (Draco) and his on-screen henchmen Jamie Waylett (Crabbe) and Josh Herdman (Goyle) join the party.
Then comes James and Oliver Phelps (Fred and George) and the rest of the red-haired Weasleys.
There's also Matt Lewis (Neville), Devon Murray (Seamus), David Thewlis (Lupin), not to mention Hedwig the owl.
Rupert is one of the first actors to chat to CBBC Newsround.
He said he couldn't quite believe it'd been four years since he was cast as Ron and admitted he'd seen a bit of the first film on TV a few weeks ago, which had "brought back some memories".
Rupert said it was cool to have some new cast members on the set of the fourth film, the Goblet of Fire, currently shooting at Leavesden Studios. Key new roles are filled by Katie Leung, who plays Harry's girlfriend, Cho Chang, and Stanislav Ianevski, who plays Viktor Krum.
"They're really nice, it's great to have some new people," he said.
Emma agreed. She has lots of scenes with Krum, who's her date for the infamous Yule Ball.
"Stanislav is genuinely lovely," she said. "I have to do some dancing scenes with him and he's actually not a bad dancer."
Emma admitted she was having formal dancing lessons for the ball scenes, including learning the tango and the foxtrot!
David Thewlis, who plays teacher-turned-werewolf Professor Lupin, said the DVD launch was a great chance to meet up with the young actors again.
"It's so nice to see them," he told Newsround. "They really are very nice kids, especially Daniel, who I did most of my work with - he is very smart, very beautiful and very funny. He is my little friend."
David added he expected to be back as Lupin in the fifth film and would be "delighted" to play the part again.
But some of the cast had different reactions when asked the big question - will they be back for films five, six and seven?!
Rupert said: "I want to do all of them if I can, they're just such good fun."
But Emma was more cautious: "Woah!" she laughed. "I've honestly no idea, no idea at all."
We'll have to wait and see!