The White Road by Sarah Lotz

I think The White Road is Lotz's strongest book so far and I've read all of her novels but one (the first). It centers on two extreme sports, caving and high altitude climbing. I expect nearly everyone knows about, has read about, seen videos of, or participated in these activities. It is in the very commonness of these elements that makes the fear and horror more real.  It isn't quiet...quiet...SHOUT horror, it's worse. It is the kind that settles in your gut and gnaws at you while you read. The caving bits are especially terrifying. Have you ever had a nightmare where you can't move and something menacing is coming? It's like that. The book gave me a very visceral feeling of claustrophobia and the realization that I'll never be a caver, or high altitude climber for that matter.

Summmary: Simon Newman gets a sketchy guide named Ed to take him into the Welsh cave system, Cwm Pot, on a tasteless mission to boost traffic to the website he co-owns, Journey to The Darkside. The expedition goes tragically wrong and Simon is the only survivor and he experience leaves him traumatized. Simon's website partner, Thierry, puts video from the cave on their website and it gets the reaction they hoped. Wanting to follow up on the success from Cwm Pot, Thierry convinces Simon to tackle Everest with an equally tasteless goal. The action then shifts between Simon on Everest and a previous expedition. Simon comes off the mountain with a severe case of PTSD and the unsettling feeling that events on Everest are related to his near-death experience in the cave. 
This is a excellent book and I recommend it, particularly if you like intense suspense mixed with fear ahd horror. 

The White Road is available for Kindle and in print at Amazon.

One last thing. Lotz went to impressive lengths to understand the technical details in her book. She traveled to Nepal and Tibet and to Everest Base Camp. She also went caving. There is a video of her caving experience on YouTube— Sarah Lotz Caving. Bonus: that's her husband Charlie standing behind her at the beginning of the video. Now that is support.