there is no known thriller novel titled "The Lonely Musketeer" written by an author named Nicolai Schumann. It's possible that such a book may have been released or gained prominence or that the title or author's name is different from what you provided.
If "The Lonely Musketeer" is a newer or less well-known book, I would not have information about its premise or content. To get accurate details about the book and how it explores human trauma, I recommend checking with reliable book review sources, online bookstores, or the author's official website (if available) for more information.
Alternatively, if you have any other book or author in mind that explores human trauma, feel free to ask, and I'll do my best to provide relevant information based on the data available .