Warbound — Larry Correia

Gritty urban fantasy set in an alternate noir 1930s. A tough P.I. battles an interdimensional monster that wants to suck magic power out of the world. Sequel to "Hard Magic "and "Spellbound. "Book Three in the Grimnoir Chronicles.

Gritty urban fantasy adventure set in an alternate noir 1930s, Book Three in the Grimnoir chronicles.
Only a handful of people in the world know that mankind s magic comes from a living creature, and it is a refugee from another universe. The Power showed up here in the 1850s because it was running from something. Now it is 1933, and the Power s hiding place has been discovered by a killer.
It is a predator that eats magic and leaves destroyed worlds in its wake. Earth is next.

Former private eye, Jake Sullivan, knows the score. The problem is hardly anyone believes him. The world s most capable Active, Faye Vierra, could back him up, but she is hiding from the forces that think she is too dangerous to let live. So Jake has put together a ragtag crew of airship pirates and Grimnoir knights, and set out on a suicide mission to stop the predator before it is too late.