Chris Ryan 
Endgame 

‘Don t come after us remember the first thing I ever taught you – that your first duty is to stay alive’For some time now, Zack Darke has been operating solo, in total secrecy, for a shadowy government organisation. When his handlers are abducted by somebody with a serious personal vendetta against him, Zak has no choice but to go after them. And heading across the world to find them – into danger like he’s never known – is something that, this time, he cannot do alone . . .