A Darker Shade of Magic

by V. E. Schwab

As a young Antari magician, Kell is one of the last magicians with the rare ability to travel between the four parallel Londons, which he calls Red, Grey, White, and Black.

Kell officially serves the royal family of Red London, The Maresh Empire, as an ambassador, traveling between worlds to deliver messages, letters of importance and other such news. However, Kell has a secret life as a smuggler, servicing people willing to pay for even the smallest glimpses of magic. It's a risky pastime with dangerous consequences.

After a smuggling job goes wrong, Kell escapes to Grey London where he finds Delilah Bard, a young thief looking for a taste of adventure and a chance at something more. Delilah first saves Kell, then captures him and talks him into going with him. In a world with magic, it's of course unavoidable that things go horribly wrong along the way.