Peter Cheyney 
It Couldn’t Matter Less [EPUB ebook] 

It’s wartime London. Inspector Gringall of the Yard, long-time friendly rival of private detective Slim Callaghan, sends Slim on a mission to meet Doria Varette, a torch singer at Ferdie’s Place.Callaghan knows Gringall has something up his sleeve. And when, backstage, Doria asks him to take on a job — to find her boyfriend Lionel Wilbery, a poet with the wrong friends and a drug problem — Callaghan finds Gringall has more than a missing person in his sights.