The Lost Soul by Jen Talty

Hunter Knight should be dead. His body and mind are so damaged after being tortured by an underground group of psychic operatives, it would be a miracle if he not only survived but came back as a whole man.
Alexis Raven will do whatever it takes to ensure the Collective Order is reinstated, even if it means risking her life, following Hunter through the abyss and into the past. It is there they uncover the mystery behind the birth parents of the quadruplet brothers. It comes as shock to Hunter that his biological father had been right in front of him for years. He will be forced to put his anger aside when his own father, in the present, disappears.
Hunter and Alexis are given only pieces to the puzzle. They must use their new abilities to track Hunter’s biological parents and free a tortured soul. If they fail, the Collective Order will cease to exist, and Hunter and Alexis will perish.