Leviathan (Caster: Where Demons Dwell, #5)

Cast ye who is without sin! After discovering that demonic creatures exist, Danny Matthews, by chance or providence gains the power to fight demons and becomes Caster. Danny and Nina finally get the much-needed help in the form of the enigmatic Doctor Brimstone and Suri, the first Caster Danny ever met. Will they discover a way for Nina’s soul to re-enter her body? Who is Doctor Brimstone and how does he know so much about Casters? Where do souls go when they cannot move on to the afterlife and cannot yet return to their bodies?