Watch Online Free on Watchseries. There are 500 tunnels under Los Angeles. There is no map, no guidebook, only rumors passed from one urban explorer to another. Ghost stories. Ten years after losing her best friend underground, Mika has built a career turning mystery into content. As she prepares to log off for good, the missing girl returns, drawing Mika back to the place where it all started. If Mika can survive, she will finally learn how deep the tunnels go.