Servants of the Nexus. The Wayfarer Chronicles, #1

There are a thousand thousand realms in the Nexus. Someone has to protect them from themselves - and each other. As a Wayfarer, one of the immortal Kin, it's Saenumandua's job to police the illicit sale of information between worlds. Trouble is, only another Wayfarer could do the selling, and rogue Kin are dangerous beasts. When one of them breaks into Saenu's home, she's left chasing a trail of clues that leads her to the city of Howl, a place of lumbering automatons and neon streets.
With the aid of fellow Wayfarer Cam - and his guardian angel - Saenu must take back what was stolen and face an old foe, one who leaves nothing but devastation in his wake.