One mistake.
That is all it takes for the most well-laid plans in the universe to suddenly and catastrophically implode in one's face.
It was said that the famous assassin Jing Ke became famous because of how badly botched the asssination attempt went when he tried to kill the mane who would become the First Emperor of China. His assistant froze up like a deer in headlights and the timely use of a physician's throwing arm stopped him from stabbing the man with a poisoned dagger.
The Spartan army fell at Thermopylae pass because of a traitor showing the Persian army a hidden shepard's path.
The Titanic sank because they didn't account for the cold when they decided to ram a glacier.
All it takes is one miscalculation, one overlooked factor, one mistake, and a moment of assured victory can suddenly go sideways.
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