The Last Hunter: Lament (Antarktos Saga #4)
by Jeremy Robinson (2013)

In all the days since my kidnapping, breaking and transformation into a hunter at the hands of the half-human, half-demon Nephilim, my life has been a mass of chaotic actions and reactions to the horrors of the Antarctic underworld. I have battled unnatural monsters, fled for my life, and sacrificed everything — or thought I had, when I stepped through the gates of Tartarus. Every choice I have made was in response to forces beyond my control, lacking any kind of direction.

But now, reunited with my friends, Kainda and Em, and in the company of new friends, Wright and Kat, I am taking control of the chaos and choosing my own direction — down. Deeper than the realm of Hades, the most feared of the Nephilim, deeper than the gates of Tartarus and deeper than any human being has ventured since the beginnings of the human race.

I enjoyed this less than the previous books. It suffers from a lack of clear objectives for the characters. It feels like a series of battles with no real objectives. Hopefully this will be all focused on the next (and final) in the main series.