Shadow in the North has a large cast of characters, some of whom play briefly prominent roles and then fade into the background. Theater stagehands, street urchins, and titled members of British society intermingle freely with the main characters, each adding some color to the story and filling in another piece of the puzzle. The main players in the story remain the focal point, however.

Most prominent in Shadow in the North is Sally Lockhart, a forthright young woman with a background in "firearms and finance," but not possessing the skills to "make small talk, dance gracefully, [and] flirt with a stranger at dinner while unerringly picking up the right knife and fork."

Sally insists on being in the center of the action, but she would rather not rush into a situation blindly. Before confronting Axel Bellmann, she researches his firm and puts together her own...