The Notebook hunk penned the script for sci-fi thriller How to Catch a Monster and he has cast sexy Mendes as Cat, the head of the Big Bad Wolf Club in the film, according to movie news site Bloody-Disgusting.com.
Gosling's Drive co-star Christina Hendricks will portray lead character Billy, a single mother of two who gets sucked into a fantasy underworld.
Production on the movie is due to begin in May (13).
The Hollywood couple began dating in 2011 after meeting on the set of upcoming film The Place Beyond the Pines.
