The Darkest Hour is a tense apocalyptic thriller centering on the fight for survival waged by five youths who find themselves stranded in Moscow during an alien invasion. As the invisible extraterrestrials absorb all of Earth's energy and life forms, finding a means of escaping the unstoppable attackers becomes a seemingly impossible task.

After multiple dirty bombs are detonated, spreading deadly toxic ash across Los Angeles, Brad (Rory Cochrane) inadvertently quarantines his wife, Lexi (Mary McCormack), outside their home by safely sealing himself inside. With the city under siege and Martial Law in affect, Brad and Lexi struggle to survive with few supplies, less time and no information- all the while separated by thin doors and thinner sheets of plastic. When help finally arrives, it's anything but.