"When an old and distinguished person speaks to you, listen to him carefully and with respect – but do not believe him. Never put your trust in anything but your own intellect. Your elder, no matter whether he has gray hair or lost his hair, no matter whether he is a Nobel Laureate, may be wrong... So you must always be skeptical – always think for yourself." --Linus Pauling
The movie is based on parts of two novels from a twenty book series written by Patrick O'Brian. The books are set during the Napoleonic War and follow the fortunes and failures of two men: Captain Jack Aubrey of His Majesty's Royal Navy and his ship's surgeon Stephen Maturin.
Jack, nicknamed "Lucky Jack" by his men, is a master of his chosen profession. He's a tactical genius at sea, and knows how to make one of the 'big ships' (the most complicated technology of the time) do anything he wants it to. On land is a different story; with firm ground beneath his feet and society all round him, Jack inevitably becomes well, a bit of a dork. He also plays a fair violin.
Ship's surgeon Stephen Maturin is cut from a different cloth: He's Irish and Catalan, a naturalist fluent in many languages and sciences, and a spy for His Majesty's Government. In his own way, Stephen is as deadly as Jack, capable of brilliant manipulations and schemes worthy of a Macchiavelli. He's also a dab hand at the cello.
The two, while being opposites, are also the very best of friends.
The movie does something difficult and manages to capture the feel of O'Brian's world and the people who populate it well. It is the first movie I think I've ever seen that seems aimed at the "highest common denominator."
O'Brian did not merely write sea stories by the way. He books seemed to want to describe the whole of society at the time. Mary Renault called them "the finest historical novels ever written." (Something she herself is accused of having done.) Walter Cronkite called the books "crack cocaine for intellectuals."
David Mamet wrote a great essay about O'Brian for the New York Times.
The books, and the movie are well worth your time.