The story picks up from the end of Blue at the Mizzen, when Jack Aubrey receives the news, in Chile, of his elevation to flag rank: Rear Admiral of the Blue Squadron, with orders to sail to the South Africa station. This new novel, unfinished and untitled at the time of O'Brian's death, would have been a chronicle of that mission, and much else besides.
As the novel opens, we are able to visit these friends we have followed so very far in a rare state of almost perfect felicity. Jack has seen his illegitimate son ably discharging important duties. Sophie and his daughters are with him; Brigid is with her father, she's thriving, and Stephen is with a woman who is very dear to him. Jack, at last, is flying a rear-admiral's flag aboard a ship of the line.
And so this great 'roman fleuve' comes to an end with Jack, with his 'sacred blue flag', sailing through fair, sweet days - Stephen with his dissections and new love, Killick muttering darkly over the toasted cheese....
Of course, we would rather have had the whole story; instead we have this proof that O'Brian's powers of observation, his humour and his understanding of his characters were undiminished to the end.