Os Exércitos da Memória de John Barnes. Trecho da Wikipedia:
Several attempts are made on Giraut's life as he works on his new Ix cycle of music. He is sent back to Wilson, his home planet and culture of Occitan, to complete the new music along with his Office of Special Projects team as protection. Paxa retires from the OSP and leaves Giraut after finding out she cannot be successfully backed up on a psypyx, which would make her death permanent. Giraut begins to fall in love with a fellow musician Azalais who introduces him to Ebles, a contact for rogue colonies outside of Council space which call themselves the Union. Soon after, Azalais is killed and Giraut is severely injured in another assassination attempt.
Faz parte da série "Mil Culturas" e envolve "o springer", um "método de transporte instantâneo que reúne rapidamente a humanidade em todo o espaço conhecido". É o quarto e último livro (até agora) da série.