Neon mentioned ties to Mossad. M = Mossad?
Probably. This is the book neon is discussing:
https://www.amazon.com/Robert-Maxwell-Israels-Superspy-Murder/dp/B001G7RC98/ref=sr_1_2?crid=3NILB8IUE751K&keywords=robert+maxwell+israel%27s+superspy&qid=1562724558&s=gateway&sprefix=robert+maxwell%2Caps%2C318&sr=8-2