'Z for Zachariah' Trailer: Jealousy Turns Into a Postapocalyptic Nightmare (Video)

"This guy could be anybody, for all we know."

It's the end of the world as we know it — but Margot Robbie isn't feeling too fine, if the trailer for postapocalyptic thriller Z for Zachariah is anything to go by.

Robbie plays Ann, a woman who survived a nuclear war and believes herself to be the last person alive — until Chiwetel Ejiofor appears. A scientist suffering from radiation exposure, he and Robbie's character bond — until the appearance of a third survivor, played by Chris Pine, brings a new era of paranoia and suspicion. Is it a love triangle or something more deadly?

The movie, to be distributed by Roadside Attractions, was shown at Sundance. THR's review noted that, "on a moment-to-moment basis, the three actors seem entirely engaged with their roles, but the electric currents between them are not strong and constant."

Directed by Craig Zobel and based on Robert C. O'Brien's 1974 novel of the same name, Z for Zachariah opens in theaters Aug. 21, 2015. Watch the trailer above.