Twain's plot is set in motion when a slave named Roxy exchanges her light-skinned son Chambers with her master's baby, Tom. Roxy's child, now known as Tom, grows up as a spoiled, privileged white man, who is horrified when Roxy tells him the truth. He nearly gets away with a vicious crime, but his downfall comes in the form of a clever, eccentric lawyer, nicknamed "Puddn'head" Wilson. Twain's novel was the first to use fingerprinting to solve a crime, but its significance goes much further as an investigation into the nature of identity. When the two young men are forced to change places again, the former slave finds himself exiled to a white world where he will never feel at ease, while Roxy's child discovers that his newfound value as human property outweighs his guilt as a murderer. Despite its ironic humor and the symmetrical neatness of its denouement, Pudd'nhead Wilson is a tragedy that refuses easy answers.