A Certain Magical Index, Vol. 19 (light novel)

In the shadows of Academy City, the special team known only as Group is hard at work to solve yet another incident. The Level 5 esper Accelerator and the man who controls both supernatural and magic powers, Tsuchimikado, are investigating a case where their only clue is the word "dragon." While they struggle to find a way to make progress, a member of Academy City's board of directors bears a terrible grudge against them. Once again, Group finds themselves on the business end of a fearsome weapon!