Haunting Woods by Adalind White

Following the successful resolution of the Tourist Murders case, Skye is recruited by the Organized Crime Division to infiltrate the Russian Mafia. Her martial arts training makes her perfect for the role of an MMA fighter who joins an illegal fighting ring.
Her only shelter from the darkness is in Nick’s bed and their sex games. But even that comes to an end when it gets too dangerous to go to him.
I had no idea where I was when I woke up. The silence was punctuated by loud beeps that hurt my ears. The smell told me I was in a hospital and the rapidly accelerating beeping was probably my heart monitor. I panicked when it became clear that I couldn’t see and I couldn’t move. I tried to open my eyes, but the bandage over them was tightly wrapped. I tried to move my hand, and I felt the strap holding my wrist down. I could also feel the needle in my vein, itching and hurting, and I started to struggle against the restraints.
The door opened and someone hurried inside. Instead of saying anything they walked past my bed. I had no idea what they were doing and I pulled harder against the restraints.
“You can’t come in,” a voice next to my bed said.
“You’re ok. You’re in hospital.”
I stopped struggling as soon as I heard Nick’s voice. My heart rate, however, shot up.
Nick got used to offering her the comfort she needs while she’s in the underworld without expecting anything in return. After the intensely painful experiences of her mission, she goes back to California, trying to find her way out of the darkness. For months, he lives with the pain of knowing that each phone call from Skye will be the last one.