Warner Baxter plays Dr. Samuel Mudd, American history's most famous victim of circumstance. In 1865, Dr. Mudd, a known Confederate sympathizer, sets the broken leg of a mud-caked stranger who stumbles into his home. The injured man turns out to be John Wilkes Booth, and Mudd is accused of conspiring to murder President Lincoln. Sentenced to hang with the genuine conspirators, Mudd finds his sentence commuted to life imprisonment at the very last moment. He is shipped to Shark Island, a brutal penal colony. Subject to the cruelties of a guard (John Carradine) who hates Mudd because of his "complicity" in Lincoln's death, the doctor suffers the torments of the damned, while outside Shark Island his wife (Gloria Stuart) campaigns desperately to get her husband pardoned. During a Yellow Fever breakout on Shark Island, Dr. Mudd performs heroically to save the survivors. For his humanitarian efforts, Mudd is finally released and reunited with his wife. While the script glosses over the fact that Dr. Mudd had never been officially pardoned by the US government (the pardon wouldn't be granted until years after this film was made), Prisoner of Shark Island strives long and hard to exonerate the man for whom the phrase "your name is mud!" was coined. Dr. Samuel Mudd's story was retold in the 1952 feature Hellgate, with Sterling Hayden as a (fictional) doctor, and in the 1980 TV movie The Ordeal of Dr. Mudd, starring Dennis Weaver in the title role.
by Hal Erickson synopsis