It’s the last few vintage thriller covers:
Surely this must be the most literal cover art ever? Could it be that in their spare time the titular spies form the string section of an orchestra? And look, there’s a good old-fashioned tied up useless woman – I can’t work out whether the window lurker is a baddie leaving or a hero coming to rescue her. He looks sinister – she looks alarmed – but why would he be leaving by a window?
For a far more straightforward cover check this out: