Ryan Gosling adds Saoirse Ronan to 'How to Catch a Monster'

Casting on Ryan Gosling's directorial debut, the fantasy noir How to Catch a Monster, has picked up in earnest this week. Not only did he add his gal pal Eva Mendes, but Doctor Who star Matt Smith took on the male lead. It looks like Gosling's name is making it easier to draw top notch stars, because the latest to join is Saoirse Ronan.

Ronan, who will be seen next in The Host, joins the already cast Christina Hendricks and the newly confirmed Ben Mendelsohn in the story of a single mother (Hendricks) named Billy who gets swept up into a dark and macabre fantasy underworld while her son Bones discovers a hidden road leading to an underwater town. It sounds like ambitious material for a first time effort, but Gosling's never been one to shy away from a challenge.

Filming on How to Catch a Monster begins in May.