When this issue came out, I had just had my 11th birthday and I was starting to grow away from comics. To the best of my recollection, I never even bought this issue at the time.
Basically, Superman loses his powers (happens a lot in this title) behind the Iron Curtain and finds that there's a reward out for his arrest. The local dictatorship uses troops dressed as his friend Batman to capture him but he captures one of them instead and dresses as the Dark Knight. That, of course, is when he happens to run into the REAL Batman and the two of them get caught and stuck in a concentration camp!
The ending is cut short by yet another solo Robin reprint and this it's another two-parter.