This book was among the few I've read that manage to not lose itself in minor details; a refreshing change.
In this book, the main characters are the inhabitants of a large space station situated under the sun's corona (where is it much cooler than either the center or outer shell of the sun). Protected by a special field, the station is populated by criminals convicted of the worst crimes. Since all have had their memories erased to some degree, none of them recall how or why they committed the offenses they are accused of.
The arrival on the station of three new "convicts" after many years without much communication results in many strange things happening on the station. In a very short time, their leader is forced to deal with a past he would have rather left alone, but finds out some surprising things.
Sort of a mystery novel, as most sci-fi books are, this is among the best. (My idea of a bad book varies, but would include most of the Star Trek books, especially the later ones, written by novice authors who don't understand their subject and try to do odd things to get noticed). It's interesting all the way through, and doesn't become silly, thereby filling my major requirements.