Andrew Pyper's The Demonologist

David Ullman is a professor and leading world authority on demonic literature, with a primary focus on Milton's Paradise Lost, but that doesn't mean that he is a believer. David is asked to travel to Venice in order to give his opinion on a rare phenomenon. He initially refuses but decides to take his daughter with him when his wife decides she is leaving him. What happens in Venice will set off a chain reaction of events and sent David on a mission to save his daughter, all to be done within a certain time or risk her being gone forever.