Makers Warner Bros are hunting for a girl aged 13-16, living in Ireland or the UK, to play Luna Lovegood.
It's happening between 10am and 2pm on 14 January, at the Central Hall Westminster, Storey's Gate, in London.
Applicants should bring a passport to prove their age, and dress warmly - there could be a long wait!
Anybody who doesn't have a passport won't be seen, and neither will girls who don't live in the UK or Ireland, and Luna is the only part they're looking for.
You also need to bring something with proof of your address on to show where you live.
They're just planning to take a photo of anyone they think has the right look, and will get back in touch with some of them for an audition.
They also say girls should come as themselves - no costumes, make-up or high heels will be allowed.
The queue opens at 8am on Saturday morning, and closes at 2pm.
The full address for the audition is:
The Central Hall Westminster
Storey's Gate
Westminster
London
London SW1
The nearest underground stations are St James Park and Westminster.
You shouldn't contact the venue as there is no further information available.
