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The "Underworld USA Trilogy" is James Ellroy's renowned crime fiction series comprising the novels "American Tabloid," "The Cold Six Thousand," and "Blood's a Rover." Set against the tumultuous backdrop of American history in the 1950s and 1960s, it intertwines the lives of diverse characters, including corrupt politicians, mafia figures, and a former Marine, delving into the darker aspects of power and corruption that shape society.