When a group of teenagers receive an invite to download the latest smartphone app, an intelligent personal assistant, they expect a harmless way to get directions and restaurant recommendations. But the sinister nature of the app soon reveals itself, tormenting the friends by tapping into their darkest fears.

Columbus has made a habit of running from what scares him. Tallahassee doesn't have fears. If he did, he'd kick their ever-living ass. In a world overrun by zombies, these two are perfectly evolved survivors. But now, they're about to stare down the most terrifying prospect of all: each other.