A traffic accident sparks a devastating explosion, trapping a small group of people in the tunnel. Before them is a vision of Hell: a dim, stifling world, changed forever by a spectacular fireball that roared through the tunnel from end to... See more end. The air is foul with noxious gases and smoke, and is illuminated by toxic flames flickering eerily in the distance. Huge slabs of concrete and twisted masses of metal are everywhere as the weakened tunnel begins to collapse in on itself. Worst of all, the river churns above, its freezing waters impatient to come rushing through and reclaim its own. As more and more sections of the tunnel come crashing down behind and in front of them, the 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 (Sylvester Stallone), the disgraced former head of Emergency Medical Services, who risks his life in a harrowing journey through the tunnel’s unstable ventilation system to reach them. But once inside the tunnel, Kit becomes trapped with the others and is forced to improvise a roller-coaster ride of escape to lead the group back to daylight.
