District 9 star Sharlto Copley joins British actor Alex Pettyfer in director DJ Caruso’s sci-fi actioner I Am Number Four. The film is an adaptation of the upcoming HarperCollins young-adult novel of the same name written by James Frey (”A Million Little Pieces”) and Jobie Hughes.

The plot revolves around John Smith (Pettyfer), an alien living incognito as a human high school student in Paradise, Ohio up until he’s discovered by the extraterrestrial enemies that destroyed his home planet. Copley will play Smith’s alien protector.

Dreamworks will release the film on Feb. 18, 2011.