D.Gray-man Vol. 18 (manga)

Thief? Ghost? Innocence?

It's been three months since Allen Walker's mentor, Cross Marian, pulled his latest disappearing act. Allen and fellow exorcist Kanda now learn of an odd new threat known only as G. G plans to steal a valuable crown from the Louvre, so Allen and Kanda join the local constabulary in trying to prevent the theft. This leads to a surprise discovery that could have no small significance for the future of the Black Order!