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Citizen Kane - Wikipedia, the free encyclopedia, under the section titled Synopsis:
When wealthy media magnate Charles Foster Kane dies, he utters the word "rosebud". An obituary newsreel documents the events in his public life. The producer of the newsreel asks a reporter, Thompson, to find out about Kane's private life and personality, in particular to discover the meaning behind his last word. The reporter interviews the great man's friends and associates, and Kane's story unfolds as a series of flashbacks.
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Despite Thompson's interviews, he is unable to solve the mystery; he concludes that "Rosebud" will remain an enigma. However, the camera pans over workers burning some of Kane's many possessions. One throws an old sled, with the word "Rosebud" painted on it, into the fire – the same sled that Kane was riding as a child the day his mother sent him away. There is a shot of a chimney with black smoke coming out. For the viewer this solves the mystery of what "Rosebud" is.