This is a short story in the Seventeen series, and it follows characters we haven't seen center stage before: the Order of the Three Spears, the Buddhist, or Buddhist-adjacent, warrior monks who are loosely allied with the human-friendly faction of the immortals. (That's not altogether accurate, but it's accurate as I think I can be without spoilers.) Warrior Monk is the monk's-eye view of the episode in #2 involving the rather exciting events at an archaeological site in Egypt. When word of the reappearance in the West of an old and powerful enemy reaches the monks, they send out one of their more, ah, difficult members to investigate. These are events we've seen previously, but from a new perspective, with new things to learn about what, exactly, is going on.
It's short, quick-moving, and interesting background for the overall story and the characters involved. Recommended if you've enjoyed other entries in the series.
I bought this book.