[1] The action of the novel takes place in 1911, some time after Don Manuel, the benevolent dictator in Sard Harker, has died.

At the start of this adventure story, its narrator, the young seaman Charles Tarlton, has arrived in Santa Barbara and been recommended to take up the post of Fourth Officer on a crack trading ship.

Meanwhile Santa Barbara is being put on a war footing, a boom closes its harbour off and the naval police regularly patrol it.

However, Tarlton is a gifted pilot and remembers once reading about a hazardous channel, known as Drake's Passage, that provides an alternative escape route out of the harbour.

He also persuades his cousin to dress up as an admiral and commandeer The Gry, with The Shining Branch to tow it away under cover of darkness and fog.