Olivia Thirlby has joined the cast of The Darkest Hour. The story follows a group of Americans traveling in Moscow when an alien invasion occurs. Thirlby will play a girl who teams up with others to try to defeat the invaders. Chris Gorak will direct from a script written with Josh Zetumer. Timur Bekmambetov will serve as one of the film’s producers. Filming begins this summer in Moscow. Thirlby’s credits include Juno and The Wackness.