Martin Walker: The Infiltrator (UK 1979)

From the publisher:
THE DICTATOR IS DEAD.
THE PEOPLE ARE FREE.
THE COUNTRY IS THERE FOR THE TAKING...
Portugal 1975 - the impoverished country is at boiling pitch, and violent revolution is about to erupt.

London dispatches David Maddox to lend a helping hand to the course of events. Armed with eighten months training in revolutionary tactics and an endless supply of heroin, he is accompanied on his highly dangerous top secret mission by Marianne, a clear-eyed athletic American girl. But he can't decide whether she's the best thing ever to happen to his life, or whether she's a CIA plant who loves her work and just happens to be very good at it...

Martin Walker: The Infiltrator. London: Panther Books, 1979, ISBN: 0586045724, 252 p., 95p.