In
upstate New York, barrels of volatile toxic waste are loaded onto trucks to be illegally disposed of at a site in
New Jersey. The trucks enter a tunnel beneath the
Hudson River along with other commuters, including struggling playwright Maddy Thompson, a bus of juvenile offenders, a vacationing family, an elderly couple with a dog, and athlete Roy Nord. Meanwhile, a gang steals a briefcase of gems and flees by car into the tunnel, pursued by the
New York City Police Department (NYPD) after the gang are tracked by the victim's Electroguard-protected car. The gang loses control of their vehicle and crashes into one of the waste trucks, causing an explosive blast that seals the tunnel off from the outside, fills it with toxic gas, and kills dozens of commuters. Caught on the outside of the tunnel collapse, former New York City Emergency Medical Services Chief Kit Latura, now working as a taxi driver, rushes to help whomever he can. Encountering his former EMS colleagues, Kit suggests intentionally collapsing the roof to protect the trapped survivors from the fumes, but is dismissed by their commander, Wilson, who is killed when the unstable tunnel collapses further. Kit enters the sealed tunnel through the ventilation system, risking his life as the fans can be slowed down for only a short time. Survivors band around Nord, who believes that he can exit through the mid-river passage, a service corridor running between the north and south tubes. Kit arrives and warns Nord that the passage could soon come down, but Nord dismisses the possibility. Kit escapes as the passage collapses, killing Nord and causing another explosion which kills a juvenile offender. Water begins seeping in from the river above, and Kit uses an explosive to stop the leak. Police officer George Tyrell returns from investigating the Manhattan end and is crushed under a truck as the road shifts. The group frees him before he can drown, but he is left with a broken neck. The water level continues to rise, and the angry survivors confront Kit. He claims that he can slow it down but not stop it, as the clean-up effort on the Manhattan side of the tunnel is causing water to enter their side. There are sleeping quarters beside the tunnels (leftover from the tunnel's construction), and Kit asks George how to access them. Kit finds one by swimming under a security booth and leads the group to this area, but George has to be left behind. He gives Kit a bracelet intended for his girlfriend Grace. Elderly survivor Eleanor is distressed that her late son's dog Cooper is missing. She refuses to go on, then passes away, presumably from
hypothermia. The group moves to another room as the first one floods, convincing Eleanor's husband Roger to come with them. As they reach the top of an old wooden staircase, Kit notices Cooper swimming in the water below and dives down to rescue him, passing him up to a survivor, but a beam falls and destroys the lower half, sending Kit into the water. Maddy tries to help Kit up, but she falls as well, as more of the staircase is knocked down. Kit orders the rest of the group to leave. The majority of the group escape through a manhole into daylight while the corridor caves in behind them, leaving Kit and Maddy behind in the rising water. Kit and Maddy swim around looking for an exit, with the main highway tunnel now almost completely submerged. Kit realizes that he will have to use his explosives to cause a "blowout" and rip the tunnel roof open. A mass of mud crushes Kit, and Maddy tries to pull him out. The blast forces Maddy towards the surface, but Kit gets stuck in the mud. Maddy finds a barely conscious Kit and keeps him afloat as a boat discovers them offshore. Lying on a stretcher, Kit sees Grace in the crowd and hands her George's bracelet. Maddy insists on riding with him in the ambulance; Kit agrees, but suggests on one condition: “We gotta take the bridge.” ==Cast==