Killmaster Nick Carter and a rookie agent go undercover to break up a heroin ring in The Mark of Cosa Nostra, an early 70s installment in the long-running spy series.
I picked this up as part of my casual re-read of the Nick Carter paperbacks that I enjoyed so much as a teenager. This one was actually written by George Snyder, who penned lots of men's adventure stories.
Carter and his attractive young partner--armed only with a pair of specially-built panties with a spring-loaded single-shot pistol built in somehow--pose as a mafia boss and his girlfriend to unravel an unlikely, knotty plot involving the Chinese trying to take over the drug traffic into VietNam by controlling a branch of the mafia.
Convolutions aside, this is a burly, fast-moving story with an especially breakneck ending, where a badly wounded Carter tries to dispatch some baddies and free his partner. Enjoyable enough if you can ignore the broad strokes in which some characters and situations are portrayed in that moment in time.
I have a big stack of these Nick Carter books and have been working my way through them steadily.