What I am sure of:
I read this story on paper.
The protagonist was sentenced for some (real or made-up) crime and imprisoned inside the Alps (or other mountains). The prison was special because all inmates were permanently alone, naked, in complete darkness and silence. However, the cells seemed to be at least partially natural, (maybe "carved" inside the mountain rather than "built") because there were tiny holes in the walls.
Somehow the protagonist figured out that he can barely communicate with another inmate (a woman) through these holes and the two of them plan an escape.
They escape by getting carried away in an underground stream (and falling down a waterfall ???).
The following scene I remember the best:
they get thrown out of the water by the waterfall, and the woman gets angry at the protagonist for messing it up. However, the protagonist rips out some grass and throws it on her. It means they made it outside, but it's night time, so they mistook the darkness for inside the mountain. They both laugh it out and start having sex.
The next morning they raid some clothes from a nearby farmhouse. It appears they are in France.
What I am less sure of:
The reason why our protagonist got imprisoned may have had something to do with refusing a job offer from a very powerful individual.
I think the job involved recovering a spaceship (or some data form the spaceship) that got lost in space. He wondered why they needed him, while they can hire an ESPer for "just 1 million dollars", so he refused, saying the set up is fishy.
Absolutely hazy info:
I feel like the ESPers had some special name, (the telepaths, or something, idk)
There may or may not have been tracking beacons/microchips complicating their prison escape.
I remember thinking the protagonist had a very "American" name, almost to the point of parody.
while I read it on paper, I am absolutely unsure whether it's a novel, or short story, or what... I found the book in my grandfather's house. It was a hardback, with plain teal cover (no art or anything), and I have a sneaking suspicion that my grandfather re-bound the book himself after it "lost" the first cover.
Somehow, my mind connects this story with the words "anthology" and "1970s"...
HOWEVER! As I was reading it, it was clearly split into chapters. Therefore I'm not sure if this single bound volume contained multiple books each with their own chapters, or if this was a short story in parts, or if the cover was simply lying to me...
In any case, since it was in my grandfather's possession, I can imagine that it might indeed have been published around the 1970s.