The scene is New York City, but it could be anywhere. Commuters jam the underwater tunnel linking the island of Manhattan with New Jersey. Traffic is heavy -- the usual mix of outward-bound workers and visitors, commercial and industrial vehicles, and people just passing through. All in all, a typical evening rush hour until... A traffic accident sparks a devastating explosion. As more and more sections of the tunnel come crashing down behind and in front of them, a small group of survivors -- ordinary citizens from all walks of life -- come to the terrifying realization that they may die at any moment by suffocation, drowning or fire. Their only hope is Kit Latura, the disgraced former head of Emergency Medical Services, who risks his life in a harrowing journey through the tunnel's ventilation system to reach them. But once inside the tunnel, Kit becomes entrapped with the others and is forced to improvise a roller-coaster ride of escape to lead the group back to daylight.