The Hunt - The Adventures of Marcus Kildud, #1

Lieutenant Marcus Kildud and his men are rangers for hire. They specialize in insertion, extraction, escape, and evasion. He answers an urgent request from the Planet Terrus' Prelate, the Lord Fulsam, whose son has disappeared and is presumed dead. Their task is to find the ring the Prelate's son wore. The promised compensation and bonus offered are enough to make this their team's final mission. What they meet in the forest is something none of them have ever encountered before.
Marcus now faces the unimaginable. He realizes too late that sometimes, running away may be the only option left to stay alive.