Stars from the Narnia and Harry Potter movies will be getting together this weekend.
They're going to the Thames Festival in London, to give fans a chance to find out more about their fave films.
Anna Popplewell who plays Susan Pevensie, will be chatting to festival-goers about the Chronicles of Narnia.
And Oliver and James Phelps - better known as the Weasley twins - will be giving people a behind-the-scenes look at the making of Harry Potter.
They'll be joined by the stars of the small screen too, including Daniel Anthony, who plays Clyde in The Sarah Jane Adventures.
Budding reporters and camera operators can also test their skills in the special Newsround studio, and find out more about how the programme is made.
The Mayor's Thames Festival takes place on Saturday 13th and Sunday 14th September, and the CBBC Experience tent will be on Jubilee Gardens, next to the London Eye.
Movie-making sessions are free, and are taking place from 12 pm until 7 'o' clock, but you need to book a place to take part.