Oh! It's a stalag translated into english!
I remember these being all the rage in 60's Isreal. It's a classic formula. Stockholm syndrome, eros, leather, and B/\d/\s/\m coupled with Nazi prison camps and torture. Never seen it with gays though. Usually it's more like an American soldier caught by a Female Nazi, raped tortured, then escapes by killing his captors gruesomely. Tended to pander to the just-past-puberty crowd.
Here's a link:
Picture somewhat unrelated.