Architect Doug Roberts (Paul Newman) returns to San Francisco for the dedication of the Glass Tower, which he designed for developer James Duncan (William Holden). The Tower, 1,688 feet (515 m) tall and 138 stories, is the world's tallest building. During testing an electrical short starts an undetected fire on the 81st floor. During tests in the utility rooms a detected short occurs with Roberts suspecting that Roger Simmons (Richard Chamberlain), the electrical subcontractor and Duncan's son-in-law, cut corners. Roberts confronts Simmons, who feigns innocence.
