Cate Shortland, the Australian filmmaker behind the 2012 Nazi drama Lore, is directing the project, which has a script by Jac Schaeffer.

Plot details are being kept behind the Iron Curtain, but it will be an internationally set story centering on Natasha Romanoff, a spy and assassin who grew up being trained by the KGB before breaking from its grasp and becoming an agent of SHIELD and Avenger.

Marvel could tell you who Harbour is playing, but then they'd have to kill you. (Not really. Character information for Harbour has not yet been revealed.)

Harbour is in the midst of a Hollywood moment. The actor toplines Lionsgate's comic book-based Hellboy, which is set to open April 12, and recently wrapped a turn opposite Chris Hemsworth in the action thriller Dhaka. He also will return in July for season three of Netflix's Stranger Things, in which he plays Sheriff Jim Hopper, a breakout and fan-favorite role that has garnered him Emmy and Golden Globe nominations as well as a SAG Award win.

Harbour is repped by ICM Partners and Peikoff Mahan.