A Certain Powerful Teen Titan Book 1; Dawn Of The Dead

Academy City's Level 5's have been chased out of Academy City for reasons only one of them knows.. and won't reveal. One of them managed to book them a plane, and they decide to call a truce with one another so they can leave.
However, whenever they crash land in Jump City, and beat up some bad guys, the Titans offer them a place to stay.
Robin, of course, is suspicious, and decides to investigate. . . and discovers a horrible, dark plan... that could change the Titans forever.

Raildex/Teen Titans)