Dark water

the long version

"When an Englishman, Marcus Winslow, appears at Private Investigator Makana's door one April morning, Makana does not realize that he will soon risk losing everything he has built for himself in Cairo. Winslow represents the British Secret Intelligence Services and he has a special mission to offer, one that Makana cannot resist: Ayman Nizari, a dangerous specialist in biochemical nerve agents, is on the run and asking for asylum. The only person who can bring him in is Makana--by Nizari's own request. Nizari has gone underground in Istanbul and Makana, for the first time since arriving in Egypt, must travel abroad, to a city he doesn't know. Can he trust Marcus Winslow? Or is something more sinister in the works? In Istanbul, Makana soon realizes that nothing is what it appears to be. Suddenly, his past is racing to catch up with him, and Makana becomes both hunter and hunted."--