The Run Around — Brian Freemantle

An authorized agent again, Charlie Muffin must thwart an assassination attempt that could turn the tides of the Cold War

It could be the most sensational defection of all time. The head of the Russian KGB’s cipher section comes with every code, every plot, every secret. But his most startling disclosure of all is that the Russians are planning a shocking assassination.

But the defector doesn’t know who. Or where. Or how. Or when. All Charlie knows is that he must stop the murder from happening - without being marked for death himself.