Attitude by Hal Clement audiobook.
They had been captured, but by whom? And why where they allowed to build anything they wanted to escape? The space cruiser was powerful and built to fight anything in the galaxy, but somehow, in the empty rift between galaxies, they had been rendered helpless and brought to this prison. Even stranger was that their captors had not harmed any of them at all, used no weapons and allowed them to use all equipment brought from their ship inside the prison. And did not utter a sound. Stranger and stranger. Where were they, and how could they escape? And where could they go if they did? Follow these space men as they match wits with an utterly unknown life form