Magic and Mayhem (The Warden Book 9) - The Warden, #9

A routine visit into the wizard's den puts the entire prison at risk. The prison has been swallowed up by the bubble, along with everyone inside. They are cut off from the outside world and the warden must put his trust in a former prisoner to save them. Meanwhile, a grave mistake has put the entire world in jeopardy. When the collectors fail to deliver the threat, the warden sends his hunters. Friends are pitted against friends in an effort to protect humanity from one very powerful girl.