It's April 1805 and the only thing that stands between Napoleon and world domination is the British Navy. Accordingly, Captain "Lucky" Jack Aubrey (RUSSELL CROWE) is ordered to take his warship, the H.M.S. Surprise, and intercept the French frigate Acheron. Unbeknownst to Aubrey, the French captain has come around on the Surprise. After she mounts a fearsome attack on Aubrey's vessel and crew, the Brit manages to get the Surprise into a fogbank and escape capture and/or destruction.
Aubrey's decision to stay the course and repair the ship while at sea rather than returning to port doesn't sit well with the crew, including the ship's surgeon, science officer and friend to the captain, Dr. Stephen Maturin (PAUL BETTANY).
While tracking the course of the Acheron, Aubrey pushes the crew - that includes coxswain Barrett Bonden (BILLY BOYD), Lt. Tom Pullings (JAMES D'ARCY), uncertain midshipman Hollom (LEE INGLEBY) who doesn't have the respect of those under him, sailing master Mr. Allen (ROBERT PUGH) and young members Peter Calamy (MAX BENITZ) and Lord Blakeney (MAX PIRKIS) - to their limits.
With additional violent encounters with the more heavily armored and armed Acheron as they sail around part of the world, Aubrey's determination to catch and defeat the enemy soon causes Maturin and others to question whether his motives are professional, personal or a combination of both.