A Darker Shade of Magic by V.E. Schwab
Fans of Shadow and Bone — and its companion series Six of Crows — will find a lot to love in V.E. Schwab's A Darker Shade of Magic. Kell is a Traveler, a rare magician who can travel between four parallel (but very different) worlds. Officially, he's a prince and ambassador for Red London, a place imbued with magic and ruled by an empire. Unofficially, though, he's a smuggler who doesn't discern much about his clientele — until a street thief gets the better of him and makes him her unwilling ferryman between worlds.