Club Hopping
You decide that lying isn't going to get you anywhere. You tell him your real name and tell him that the vampire had followed you from a club called the Raven. You leave out the bit about swiping the book though, instead saying a friend had 'given' it to you.
He seems to accept your answer and smiles broadly at you. Then, after laying the still twitching vampire's body out where the sun will surely be able to get it, he leads you back towards the mouth of the alley.
Once there, Liam asks you if maybe you'd be interested in learning more about his secret society.