The Adventures of Tintin: Secret of the Unicorn won't hit theaters until December 23, but there is already movement on a sequel, with Anthony Horowitz confirmed to write Prisoners of the Sun. Here's what he had to say on Richard Bacon's Radio 5 program on BBC this week.

I'm working in Hollywood at the moment, I'm writing a feature film even as we speak. I've been hired to write Tintin... RELATED: Tintin Live-Action Movie Is in the Works, Won't Be Connected to Spielberg's Movie

The Secret of the Unicorn is being directed by Steven Spielberg and was written originally by Steven Moffat, of course the writer of Doctor Who in this country. He did a couple of drafts then it was taken over by Edgar Wright... they've got [that] coming out at Christmas and if that film is a success and works and gets an audience I'm writing the sequel to it, Prisoners of the Sun, which Peter Jackson is going to direct.

Joe Cornish is also a named screenwriter with Edgar Wright... That's only three [writers]. Three is not too bad... at the moment on the second one it's just one but you can bet your bottom dollar that by the time the film hits the screen, if it ever happens next year, that I'll be joined by one or two other names there."

The Adventures of Tintin: Secret of the Unicorn combines both The Secret of the Unicorn and Red Rackham's Treasure books by Hergé. There is speculation that the sequel will combine Prisoners of the Sun and The Seven Crystal Balls books. Prisoners of the Sun centers on Tintin journeying to Peru when an outbreak occurs that seems to have a connection to a mummy's curse.