Shadow in the North is first and foremost an adventure story—fast paced, exciting, and melodramatic. The conflict between Sally's inherently twentieth-century beliefs and the time in which she lives propels much of the story's actions. Within this frame, however, Pullman interjects serious moral questions of right and wrong and good versus evil, as well as social issues that are as relevant today as they were in Victorian England. By having his characters discuss and act upon these issues, Pullman manages to let the reader know his views without preaching or talking down to his audience.

One point Pullman makes in his story remains true in both the past and the present: life is not always fair.

While many authors would not kill off a successful main character in the middle of a novel, Pullman chooses to add this piece of tragic reality rather than write a conventional happy ending where all the mysteries are solved and the detectives blithely go on to their next case. He also shows that life goes on after a personal tragedy. For Sally and the others, nothing stops when Fred dies—the business must still be run, new living quarters must be sought, and all the equipment must be replaced. Pullman's characters successfully pull themselves together afterwards and manage to continue with their lives.