Gemma Arterton had to learn how to be ''bad''.
The actress had to find her inner action hero for her latest role as a crime fighter in new movie 'Hansel and Gretel: Witch Hunters' - which follows grown up versions of the classic children's story characters after they escape the gingerbread house - and while co-star Jeremy Renner is well versed in action films, Gemma had to toughen up.
