After dealing with a rogue Guardian, Anna and her friends are left with more questions than answers. Guardians are going missing, and no one knows why. Unable to discover the reason for the disappearances on their own, they must seek guidance from a senior Guardian living in London. What begins as an exchange of information blooms into a full-blown investigation of a thirty-year-old mystery that may see them all dead by the end. As though that weren't enough, Anna herself is keeping a secret... One which threatens to destroy her relationship with the man she loves.