The protagonist, a young boy accustomed to freedom who is adopted by the Widow Douglas but kidnapped by his abusive father, Pap. He fakes his death to escape, teams up with runaway slave Jim, and embarks on a raft journey down the Mississippi River seeking freedom. He navigates encounters with conmen, helps expose a scam, and later assists Tom Sawyer in freeing Jim, ultimately choosing a life of wilderness over societal rules.