The De Havilland Comet was an absolute marvel of British engineering—the world's first commercial jetliner, promising to shrink the globe with unprecedented speed. But within a year of its triumphant launch, the planes began spontaneously exploding mid-flight in the clear blue sky, plummeting into the Mediterranean Sea without warning. The culprit was not sabotage or pilot error, but a devastating ignorance of high-altitude physics. This technical history dissects the aerodynamic catastrophe of metal fatigue. Early engineers designed the Comet with large, square windows, completely failing to understand how the intense, cyclical pressurization of flying at 35,000 feet would force massive stress to concentrate in the sharp corners of the glass. We examine the grueling, unprecedented underwater salvage operations and the massive water-tank stress tests that finally proved how microscopic cracks caused the fuselage to violently unzip like a balloon. Study the deadliest physics lesson in modern transportation. Understand how a simple geometric aesthetic choice forced a total revolution in global aerospace engineering.