After some preliminaries about the main character's childhood, the novel covers a time period from roughly 1805 to 1816. This corresponds to the time period when the author was a midshipman and lieutenant in the Royal Navy. The story is told in a narrative fashion by the main character, Frank Mildmay, and draws on the author's own experiences.
Readers looking for lots of naval action will be disappointed. Much of the story is on land and deals with Mildmay's romantic involvements. A large part of the "at sea" portion of the story concerns relationships between Mildmay and other individuals. The story often digresses into philosophical thoughts. It is apparent that the author was from an upper class family, and that he looked down on people from the "lower classes" who he considered poorly educated and not up to par, i.e., his social inferiors. The rapid rise of Mildmay from lieutenant to commander was due to influence, which undoubtedly accounted for the author's own rapid promotion.
There is little naval action in the latter part of the novel as Mildmay becomes involved in a triangle between himself, his former mistress, and his future bride. He heads downhill towards self-destruction, and the story becomes a tragedy, but Mildmay is redeemed at the end.