The Hexologists — Josiah Bancroft

From one of the most exciting and original voices in fantasy comes the second book following the adventures of the Hexologists, Iz and Warren Wilby, as they tackle a case that could redefine the nature of magic itself.

As the nation's foremost investigators of the paranormal, Isolde and Warren Wilby are accustomed to bumping up against things that go bump in the night. They have made quite a name for themselves as the Hexologists: detectives of the uncanny, the monstrous, the strange. After a decade of wedded bliss and dozens of fantastical adventures, there is little in the world that can still surprise them.
 
But when a famous artist dies under suspicious circumstances, Isolde finds herself investigating a murder that may not have happened, and a crime scene that seems to shift beneath her feet. Not one to be easily thwarted, Isolde is compelled to take greater and greater risks in pursuit of her elusive answers. Meanwhile, the laws that govern magic appear to be breaking, and those cracks are spreading to the everyday world.
 
The mystery will carry the devoted duo to seedy underworlds, enchanted gardens, and subterranean military zoos. Old friends will come to the Wilbies' aid as they infiltrate secret societies, battle vicious imps, and flee from a pack of venomous wolves. Equipped with Isolde's hexes, Warren's muscle, and an enchanted bag full of magical relics, the Hexologists will have to risk life and limb to unravel the riddle at the heart of A Tangle of Time.  
For more from Josiah Bancroft, check out:

The Books of Babel

Senlin Ascends
The Arm of the Sphinx
The Hod King
The Fall of Babel

The Hexologists
The Hexologists