In a way that it's one giant story that felt epic, probably divided to trilogy if they ended up being too long for a single book.
Not episodic 20+ volume story, where one book is about one case, or a chapter of the protagonist live, the end is nowhere in sight and the reader don't care that much because each book is a self contained story. You know what I'm talking about.
Anything like Lord of the Ring, except modern day with no magic, but guns, explosion and hand to hand combat
by MmntoMri