Slow-burn espionage thrillers

I’m looking for thriller novels with espionage and a bit of action that lean more towards John LeCarre, and less towards Vince Flynn. I’ve already read a lot of Ludlum, and started reading the Slow Horses books (Mick Heron). I’m looking for stories that have spies, assassins, a bit of badassery, etc. but are less focused on being a series of exiting action-packed moments, and go deeper into character psychology, keeping me guessing as to who can be trusted, who will betray, what makes the characters tick, etc. Contemporary settings are preferable, but I’ll read older books (I really enjoyed Gorky Park and The Matarese Circle – that trope of making people from opposite sides collaborate to fight a greater threat is one of my favourites.) . That isn’t to say I don’t like action – I love a well-crafted fight scene – it’s just that I’m looking for books where the balance is shifted slightly from that.

Things I like:
Clever, resourceful protagonists who think their way out of problems
Villains with complex personalities and reasonable (which doesn’t mean ‘justified’) motives
K1lling and violence treated as moral themes to be explored
Characters with layered, complex psychology
Realism regarding plausible action/consequences
Clever spy-gadgets, especially if inspired by real life, or are firmly within the bounds of the technology of whenever it is set.
Interesting locations that are well-described and atmospheric.
People who ought to be enemies who end up working together for a common purpose and find their similarities.
Backstabbing, treachery, shifting allegiances and twisty betrayals.

Things I don’t want:
Where the antagonist’s plot is very grandiose – I’m not sure where the line of ‘implausible’ stands, but I felt the conspiracy of ‘The Matarese Circle’ was right on the edge of it.
Sci-fi spy gadgets unless the setting is explicitly science-fiction (nothing inherently wrong with it, just not my preference)
Romance sub-plots
Protagonists who can fight an endless army of mooks without consequence (I enjoyed John Wick, but it’s just not the vibe I’m going for with this)

I don’t mind the geographic location, but I’d prefer more contemporary (or at least ‘were contemporary when they were written 40 years ago’) rather than historical settings.

by HeilanCooMoo