A Darker Shade of Magic | book review

In the year 1819, Kell is one of the last Antari, blood magicians that have the ability to travel between the four worlds. In each world lies some version of London, which is how Kell differentiates between them all: Red, White, Black, and Grey. When a dangerous item from Black London finds its way into Kell's hands, he knows immediately the danger it . . .