Many years ago, a volcano erupted. Some volcanologist waited until the last minute to get out. Ashes, rocks and fire fell everywhere. One of the rocks hits Marian, killing her.

Four years later, the surviving geologist, Harry, is notified to check out a mountain showing seismic activity called Dante’s Peak. Mayor Rachael is giving a speech. At the same time, some teenagers swim in the hot springs. It gets very hot very quickly and kills them. Mayor Wanda agrees to show her around the mountain, but she first has to pick up her son Gram and her ex-mother-in-law Ruth.

Once at the top of the mountain, check the acidity of the small lake and take note of some dying trees. Then the kids notice some dead squirrels. Ruth tells them that lately the squirrels have been dying. They then find the bodies of the dead teenagers.

Harry’s team and their boss, Paul, appear. Paul recommends that they do more testing before alerting the city. The alert alone could put the small town out of business. Mayor Rachael invites Harry to dinner since he saved Grandma from jumping into the deadly water. Harry tells Rachael about Marian.

The next day they measure the sulfur in the mountain and install seismometers. They also take a malfunctioning robot to take pictures. A small earthquake destroys it and breaks a volcanologist’s leg. It is decided that the volcanologists can observe the mountain from Oregon, and they decide to leave in the morning. Harry spends one last night talking to Rachael when they notice that the water has turned brown and smells of sulfur. They visit the water supply facility and find that groundwater is getting into the tanks. The volcanologists decide that the mountain shows the same signs as the one that killed Marian. It’s time to call a town meeting to discuss the evacuation.

During the town hall, the volcano begins to blow and an earthquake is felt. The earthquake collapses buildings and interstate ramps. Everyone panics and people get trampled. Harry and Rachael drive fast to pick up their two children. When they get home, they find that the children have taken the car to look for their stubborn grandmother. They go after the children in the hope that they will have enough time before the volcano explodes. Landslides take out the road. They find the children and the grandmother. The house bursts into flames from the lava flows, so they run to the dock and get on the boat. As they walk away, they notice that all the fish in the lake are dead, and the water begins to eat away at their metal boat. Then the metal propeller is eaten and they are trapped a few meters from the shore. Will they ever make it out of the lake alive? Will they make it down the mountain to a safe place before the volcano explodes? Watch and discover.