The Old City (City of Whispers, #2)

In the sequel to City of Whispers, Ailis, Scott, and James travel to London to search for Ailis's sister, Nina, and Richard Ashdown's son, Tommy. Ailis hopes for a quick rescue, but nothing goes as planned. As she becomes increasingly frustrated, Ailis is haunted by memories from her past, and a growing feeling that there may be more to the vampire outbreak than she first believed.