Ten years together. Still in love. Spark no longer there. When their therapist suggests they visit The Castle—an exclusive, invitation-only club, Nikita and Ethan go looking for a spark. They find an inferno. Ethan discovers he doesn't just want Nikita—he wants to control who has her. Every touch he permits. Every moan he orchestrates. Nikita finds herself craving exactly that—to be wanted, watched, and completely surrendered to his command. But when a familiar tattoo catches the light on a blindfolded stranger's arm, everything shifts. Someone has been guiding them from the beginning. Someone who knows their darkest desires better than they know themselves.