Something From The Nightside

This first title in a new fantasy series introduces private detective John Taylor, who's hired by a wealthy woman to find her missing teenage daughter. To find her, he must descend into the Nightside, an otherworldly realm in the center of London where fantasy and reality share space. Original.

John Taylor is not a private detective "per se," but he has a knack for finding lost things. That's why he's been hired to descend into the Nightside, an otherworldly realm in the center of London where fantasy and reality share renting space and the sun never shines.
For John Taylor, there's no place like home...