Her Demonic Angel by Felicity Heaton

A demonic angel with a heart of ice, Veiron walks a dark path with vengeance on his mind. Nothing will sway him from his mission to destroy his master… until he risks his life to enter Hell once more to save a mortal female. The fiery beauty makes him burn with hungers he must battle and needs he cannot deny, tempting him to surrender body and soul to her.
Erin is convinced her refusal to do the Devil’s bidding will see her die in a terrifying realm straight out of her nightmares. The last thing she expects is the lethally sensual warrior who breaks into her cell and awakens the darkest desires of her heart and a fierce longing to know the heat of his caress.
Pulled into an incredible world where war is set to ignite and darkness is on the rise, Erin races with Veiron to escape the Devil’s legions in a journey fraught with danger and filled with passion that flares white-hot.
When Erin is faced with a life-shattering realisation and an extraordinary destiny, will their love give them the strength to battle both Heaven and Hell or will they be parted forever?