The Book of Betrayal (The Last Oracle, #5)

Helena Davies knows all about keeping secrets.

Now her secrets will come to light.

Helena’s encounter with a terrible creature whose kind are bent on destroying the world revealed a terrible truth: a cabal of rogue humans works with those monsters, intent on gaining power. Charged to remain silent while her superiors prepare to attack the traitors, Helena fears trusting her friends, her colleagues, even her secret lover Malcolm Campbell. Any of them might betray her.

When an unexpected attack by the hidden enemy devastates magi around the world, it draws Helena deeper into the web of conspiracy. With Malcolm suffering his own loss, and friends betraying friends, Helena confronts the reality that no secret can last forever.