Doing Business

From Goodreads:

This quirky, charming little thriller features as its protagonist a most unlikely sleuth for a pop novel--Gordon McKenzie, mathematical genius, diminutive and unattractive, with a especial penchant for London "rent boys" (i.e., male prostitutes). During one of his frequent forays into a sleazy SoHo gay bar, Gordon accidentally stumbles upon the murder of a brewery inspector in progress. He recognizes one of the assailants as a "rent boy" who often hits him up for cash. And the rent boy knows Gordon knows and proceeds to attempt to silence him for good. Gordon is on the run, aided by a handsome male prostitute with whom he has fallen in love. In the meantime Gordon is convinced the murder is part of a conspiracy involving drugs and that one of his social-climbing friends is the mastermind behind it. But just which one? And will Gordon live to find out?