Lord John first meets Stephan von Namtzen, a Hanoverian captain, in London at one of his mother's musicales. His first impression of the German is that he is loud and uncouth, but it is improved by later events, in which von Namtzen assists Grey in the pursuit of the man who poisoned him, as well as the truth about a matter which may have deadly consequences for the army. These finally being resolved, von Namtzen invites Grey to be seconded to von Namtzen's regiment in Prussia. There the two men become friends, and Grey suspects that the German may be inclined to more than that in their relationship, but does not act on it.
While in Prussia on a later campaign, Grey hears that von Namtzen suffered an accident which resulted in the amputation of one of his arms. Grey next visits the Hanoverian at the latter's hunting lodge, a place called Waldesruhe, while recovering from an injury sustained during battle, only to find that Stephan has taken to engaging in dangerous enterprises – much to the horror of his servants. Grey talks to Stephan about the incident involving Percy Wainwright and one of von Namtzen's Hanoverian officers, which leads to talk of stories about King Friedrich's male lover. After, Grey asks to see the stump of Stephan's left arm, and kisses it. Though the moment is intimate, and Grey feels more certain about Stephan's personal inclinations, he decides not to act further, having realized that Stephan's state of mind is still fragile and not up to the task of acknowledging that part of himself.
Grey next sees von Namtzen, again in London, in 1760, while the Hanoverian is in town to place his children with his sister after the death of his wife. When they retire together to Stephan's rooms, Stephan makes the first move on Grey, and they have sex.