I was struggling to remember which novel I'd read that reminded me of the Takeshi Kovacs series and finally I delved into my book collection and found Vickers again. The authors work history is somewhat illuminating.
Anyhow, hardened mercenary/killer working for a corporation goes undercover, an end of the world staged scenario and a teenage boys megalomaniacal daydreams setting up for some ultra violent adult reading. Sex, drugs and exploding bodies coming out of the New Wave of the 1980's.
Not a huge book for its time, only about 270 pages, can read in one sitting if you have an evening free. Reasonably satisfying (for an adult reader)