Consider Phlebas
The first book of the Culture series, this exciting adventure can’t hold a candle to its successor, The Player of Games. John Clute (Encycloped of Science Fiction) gets it exactly right: this is the story of a mercenary who chose the wrong side, and who fights for the conventional heroes of space opera against an enemy who are simply better. Here we see the Culture from outside and we do not always view it with sympathy; it shelters ghastly cannibal cults and seemingly stands for little save sybaritic pleasure. Only in the epilogue do we sense that pleasure is not necessarily so bad, nor does eternal struggle toward an illusory goal accomplish much beyond destruction.