During the Napoleonic Wars, Captain Jack Aubrey of HMS Surprise is ordered to fight the French privateer Acheron. Acheron ambushes Surprise off the coast of Brazil, causing heavy damage, while remaining undamaged by the British guns. The ship's boats tow Surprise into a fog bank to evade pursuit. Aubrey's officers tell him that Surprise is no match for Acheron, and that they should abandon the chase. Aubrey points out that Acheron must not be allowed to plunder the British whaling fleet. He orders Surprise refitted at sea, rather than returning to port for repairs. Midshipman Blakeney has his arm amputated due to injuries sustained in battle. Shortly afterwards, Acheron again ambushes Surprise, but Aubrey slips away in the night by using a decoy raft and ship's lamps.
Following the privateer south, Surprise rounds Cape Horn and heads to the Galapagos Islands, where Aubrey is convinced that Acheron will prey on Britain's whaling fleet. The ship's doctor, Maturin, is interested in the islands' unique flora and fauna, and Aubrey promises his friend several days' exploration time. When Surprise reaches the Galapagos, however, they recover the survivors of a whaling ship destroyed by Acheron. Aubrey hastily pursues the privateer, dashing Maturin's expectation of more time to explore.
Surprise is becalmed for several days. The crew becomes restless and disorderly, and superstition begins to take hold among them. Midshipman Hollom, already unpopular with the crew, is named a "Jonah" by the sailors (someone who brings bad luck to a ship). As the tension rises, crew member Nagle refuses to salute Hollom on the deck, and is flogged for insubordination. That night, Hollom commits suicide by jumping overboard with a cannonball. The next morning, Aubrey holds a service for Hollom. The wind picks up again, and Surprise resumes the chase.
The next day, Royal Marine officer Captain Howard attempts to shoot an albatross but accidentally hits Maturin instead. The surgeon's mate informs Aubrey that the bullet and a piece of cloth it took with it must be removed soon, otherwise they will fester. He also recommends the delicate operation be performed on land. Despite closing on Acheron, Aubrey takes the doctor back to the Galapagos. Maturin performs surgery on himself using a mirror. Finally giving up the pursuit of the privateer, Aubrey grants Maturin the chance to explore the Galapagos islands and gather specimens before they head for home. While looking for a species of flightless cormorant, the doctor discovers Acheron on the other side of the island. Maturin abandons most of his specimens and hurries to warn Aubrey. Surprise readies for battle once more. Due to Acheron's stronger hull, Surprise must be at close quarters to damage her. After observing the camouflage ability of one of Maturin's specimens, Aubrey disguises Surprise as a whaling ship; he hopes the French will be lured in to capture the valuable ship rather than destroy it. Acheron falls for the disguise and Surprise launches her attack. With the back wheels of the cannons taken off, the cannons are able to fire upon Acheron's mainmast while Captain Howard's Marine sharpshooters pick off the crew of Acheron from above. Acheron is disabled when the mainmast snaps and falls into the sea. Aubrey leads boarding parties, engaging in fierce hand-to-hand combat. Upon capturing the ship, Aubrey is informed by the ship's doctor that the French captain is dead and is given the Captain's sword.
Acheron and Surprise are repaired; while Surprise remains in the Galapagos, the captured Acheron is to be taken to Valparaíso. As Acheron sails away, Maturin mentions that their doctor had died months ago. Realising the French captain deceived him by pretending to be the ship's doctor, Aubrey gives the order to change course to intercept Acheron and escort her to Valparaíso, and for the crew to assume battle stations. Maturin is once again denied the chance to explore the Galapagos, but Aubrey wryly notes that since the bird he seeks is flightless, "it's not going anywhere", and the two play Musica notturna delle strade di Madrid by Luigi Boccherini as Surprise turns in pursuit of Acheron once more.
Commissioned Officers
Russell Crowe as Captain Jack Aubrey
James D'Arcy as First Lieutenant/Acting Captain Thomas Pullings
Edward Woodall as Second Lieutenant William Mowett
Chris Larkin as Captain Howard, Royal Marines
Warrant and Standing Officers
Paul Bettany as Dr Stephen Maturin, Surgeon
Robert Pugh as John Allen, Master
Max Benitz as Midshipman/Acting Third Lieutenant Peter Myles Calamy
Max Pirkis as Midshipman Lord William Blakeney
Jack Randall as Midshipman Boyle
Lee Ingleby as Midshipman Hollom
Richard Pates as Midshipman Williamson
Richard McCabe as Mr. Higgins, Surgeon's Mate
Ian Mercer as Mr. Hollar, Boatswain
Tony Dolan as Mr. Lamb, Carpenter
HMS Surprise's Crew
David Threlfall as Preserved Killick, Captain's Steward
Billy Boyd as Barrett Bonden, Coxswain
Bryan Dick as Joseph Nagle, Carpenter's Mate
Joseph Morgan as William Warley, Captain of the Mizzentop
George Innes as Joe Plaice, Able Seaman
William Mannering as Michael "Faster" Doudle, Able Seaman
Patrick Gallagher as Awkward Davies, Able Seaman
Alex Palmer as Nehemiah Slade, Able Seaman
John DeSantis as Padeen Colman, Loblolly Boy
Ousmane Thiam as Black Bill, Steward's Mate
Ross Boxall as Boy Drummer, Able Seaman
Other
Mark Lewis Jones as Mr. Hogg, Master of the Whaler Albatross
Thierry Segall as Captain of the Acheron
adapted from three novels in author Patrick O'Brian's Aubrey–Maturin series, which includes 20 completed novels of Jack Aubrey's naval career