Fifty years on, the Chinatown ending still empties the room. Most people come looking for the mechanics — who fired the shot that killed Evelyn, why Jake grabs the cop's arm, what Walsh means by that last line — and those answers are here. But the harder question is why the ending exists at all. Robert Towne wrote one version; Roman Polanski shot another, and the distance between them is the whole argument: about power, about American evil, about whether a story like this was ever allowed to end another way. Here's the Chinatown ending explained — mechanics first, then meaning.