After a month of back and forth, newcomer Iain De Caestecker has come on board for the male lead in Ryan Gosling’s directorial debut of “How to Catch a Monster.”

He will co-star with Christina Hendricks, with Warner Bros. on board to distribute.

Marc Platt and Adam Siegel will produce on behalf of Marc Platt Prods., along with Gosling via his Phantasma Films banner, and Michel Litvak and David Lancaster via the Bold Films banner.

Story is set against the surreal dreamscape of a vanishing city and centered on a single mother of two who is swept into a macabre fantasy underworld while her teenage son discovers a secret road leading to an underwater town. Production is set to start this spring.

De Caestecker had been the choice for some time to play Hendricks’ son, but he first had to work out his schedule on ABC’ and Marvel’s “S.H.I.E.L.D.” before he could sign on.

De Caestecker has a big year ahead of him, having already starred the Sundance pic “Fear,” as well as a nice supporting role in “Filth” starring James McAvoy. He is repped by WME and Hamilton Hodell.