While the novel is set in England in 1872, there are occasional scenes from the Orient provided by Sally's opiuminduced dreams as well as by the recollections of other characters. That Pullman has well-researched this era is reflected in his accurate descriptions and his allusions to actual events and locations. The reader is treated to an overview of 1870s England with its crime and poverty, and to a picture of a sick society with its opium dens. Although unfamiliar items such as box lock pistols, mudlarks, and hansom cabs are mentioned in the novel, Pullman explains what they are as he refers to them.

Pullman's vivid descriptions of the setting create an atmosphere of mystery and add to the feeling of suspense throughout the novel. For example, when he describes the town of Swaliness where Sally visits Mr. Marchbanks, Pullman hints at the gloom and impending danger when he writes: "The town was cheerless and cold, and the river a muddy creek that wound its way among salt flats before entering that distant line of gray that was the sea. The tide was out; the scene was desolate."

Pullman's novel is written in the style of a melodrama with the stock characters of the noble hero, the cold-blooded villain, and the virtuous heroine. While Sally Lockhart fills the role of the heroine, Jim and Frederick assume the roles of the heroes with some assistance from the Reverend Bedwell. Mrs. Holland and Hendrick Van Eeden are cast as the primary villains. Throughout the book are the typical melodramatic elements of emotional scenes, impossible situations, and dramatic chases. Also woven into the story is a look at the social evils of the time. Cliff-hangers at the ends of chapters are reminiscent of the works of serial writers of the 1800s such as Charles Dickens.

The novel consists of two parallel plots that are closely intertwined. It is only when both are joined in the exciting conclusion that the events of the novel and the actions of the characters finally fall into place. One plot is the story of Sally's quest to unravel the mystery of Captain Lockhart's death. This leads her to the shipping firm of Lockhart and Selby, to Mr. Marchbanks, then to Matthew Bedwell and Mrs. Holland, and eventually to the sinister pirate Ah Ling. The second plot is the story of Mrs. Holland's search for the Ruby of Agrapur. Tying these two plots together are the characters of Mr. Marchbanks who is Sally's real father, and Matthew Bedwell who is a sailor with information about Mr. Lockhart's death. This pattern is reflected in the overlapping motifs of the Ruby of Agrapur and opium. At times, in order to keep the action moving, the plot is a bit contrived, but this is part of the overstatement that is found in a melodrama.

Pullman is a master of description and uses figurative language throughout the novel. Clever hints hidden in the descriptions often foreshadow the events to come. For example, early in the novel, after the death of the shipping clerk, Sally returns to Mrs. Rees's home. "Without knowing it, she had shaken the edge of a web, and the spider at the heart of it had awoken." As she sits in the drawing room, "three events took place, each of which was to shake the web a little more, and turn the cold eyes of the spider toward London, and toward Sally."

Pullman has an ability to use words and descriptions to add to the mood of suspense and to heighten the tension of dramatic situations. Early in the book, as...