The Darkest Lie (Lords of the Underworld Book 6)

Forced to his knees in agony whenever he speaks the truth, Gideon can recognize any lie--until he captures Scarlet, a demon-possessed immortal who claims to be his long-lost wife. He doesn't remember the beautiful female, much less wedding - or bedding - her. But he wants to...almost as much as he wants her. But Scarlet is a keeper of nightmares too dangerous to roam free. A future with her might mean ultimate ruin, especially as Gideon's enemies draw closer - and the truth threatens to destroy all he's come to love.