When a biological bomb is discovered in the air ducts of a busy suburban mall, the entire complex is locked down, people start getting sick, supplies start running low, and there's no way out.

Among the thousands of trapped shoppers are four teens. Each has a separate story, and each copes with the catastrophe in a different way. But all of them are trying to find safety and solace at a time when adults are behaving badly.

Shay, Marco, Lexi, and Ryan learn quickly that in an emergency, people change.

And not always for the better.