Legend has it that some of the oldest surviving homeless communities in New York City have been hidden from the public view for decades in the underground tunnels of Manhattan. Many homeless dwell in continual darkness along tunnels miles long and yet manage to survive. What happens to someone who lives in such a dark and dreary dwelling? Well, Reporter Susan Pei plans to find out with the help of her friend and cameraman, Nick Murphy. As she ventures to investigate this story to impress her boss, she enlists the assistance of Tom Stranton, a local transit tunnel expert she finds on the internet. However, after he makes a miscalculation they find themselves lost underneath one of the biggest cities in the world. As they try to find a way out, they are in a terrifying struggle with the dark, with themselves and with mysterious underground dwellers that do not want them there.