It is the story of two friends, Jack Byron and Tobias Barrow, who sail aboard HMS Wager as part of the voyage around the world led by Commodore George Anson in 1740.

Some reviewers feel that the midshipman Byron and the somewhat unworldly surgeon's mate Barrow are prototypes for Jack Aubrey and Stephen Maturin, the central protagonists of O'Brian's subsequent Aubrey–Maturin series set during the Napoleonic Wars.

The expedition is beset by storms while rounding Cape Horn, and the Wager is shipwrecked off the coast of Chile when her position cannot be determined.

[1] The lesson of the wreck of the Wager played a role in revising British naval discipline, so that officers did retain formal authority over crew members even when their ships were lost or captured.

There is an "easter egg" that O'Brian includes in the novel: his version of Jack Byron secretly writes poetry, and wants Tobias to refrain from mentioning it to any of his peers.