When the skyscraper he designed in San Francisco is completed, architect Doug (Paul Newman) hopes to put aside his work and start a long-planned trip. However, at this time, an alarm signal came from the main warehouse. With the help of Harry at the building command center, Doug found out that the safe terminal cabinet had no insulation protection, and the circuits of the entire building were far from meeting his design requirements. In order to save construction costs, the building's builders Duncan and his son-in-law Roger lowered the building's fire protection specifications. Duncan and a group of celebrities from all walks of life gathered in the ballroom on the 135th floor to celebrate the completion of the building. The circuit system was overloaded and finally caused a fire. Doug and the fire captain Mike (Steve McQueen) who came to put out the fire urged Duncan to evacuate the crowd. The fire in the skyscraper with incomplete firefighting facilities soon became difficult to control. Doug, Harry and Mike's firefighters did their best to rescue the crowd, but the raging fire seemed to devour everything...