Towne based Chinatown’s script on a simple equation: he took an infamous incident in California’s history and added to it the tough style and tone of great detective novelists like Raymond Chandler and Dashiell Hammett. Polanski prepared for the movie by reading all of Hammett’s works, while Towne had read everything written by both Hammett and Chandler before he began writing his screenplay. Both men were inspired by the books, particularly in their portrait of a long-vanished Los Angeles. Even Polanski, despite his insistence that the movie not merely be an exercise in nostalgia, was insistent that the film convey a scrupulously accurate reconstruction of the decade’s décor, costume, and idioms.
Another inspiration was the public’s preoccupation with corruption. Though it did not provide any actual material for the script or look of the film, the ongoing scandal of Watergate—another incident that began with a seemingly unimportant crime that later revealed manipulation and cover-ups at a much higher level—had a powerful influence on Chinatown’s tone. When added to the brutal, senseless horrors of the Manson murders and the muddied, pointless loss of life in the Vietnam War, the America that flocked to Chinatown was much less trusting of authority and the idea of a happy ending than the country had been just a few decades before.