Architect Doug Roberts returns to San Francisco for the dedication of the Glass Tower, which he designed for contractor James Duncan. The Tower, 1,688 feet tall and 138 stories, is the world's tallest building. During pre-dedication testing, an electrical short starts an undetected fire on the 81st floor. Roberts suspects that Roger Simmons, the electrical subcontractor and Duncan's son-in-law, cut corners. Roberts confronts Simmons, who feigns innocence.