Bill James 
Halo Parade [EPUB ebook] 

The third title in the popular Harpur and Iles series. Detective Chief Superintendent Colin Harpur is disconsolate: his mistress, the widow of a fellow officer, has recently married another cop; and Ray Street, the young policeman that Colin sent undercover to infiltrate a druglord’s gang, is recklessly endangering himself. When Street is murdered, Harpur plants evidence implicating the druglord, but a clever barrister sways the jury, and the druglord goes free — free, as it turns out, to meet an altogether more basic kind of justice.