Frederick Whithers is many things--an accountant, a forger, a crook--but he is not a vampire. Not even remotely. If you lined up everyone you know on a scale from vampire to not-vampire, Frederick Whithers would be all the way at the not-vampire end, meekly wondering why he was included. But he was in prison, after all, and the best way to escape from prison in 1817 is to smuggle yourself out in a coffin, obviously, and when some actual vampires see Frederick get out of his coffin, well, it's an easy conclusion to come to.
Now the vampires are chasing him, and the constables are chasing him, and a vampire hunter is chasing him, and the list goes on and on and remember how he's a forger? There's someone else's awfully big inheritance he wants to claim, and an awfully short time to claim it, and the only person willing to help him is the capital-R Romantic poet John Keats. Yes, that John Keats. He's going to have to think very, very fast, or end up in a coffin for good.