The Ghost Brigades is a science fiction novel by American writer John Scalzi, the second book set in his Old Man's War universe.

[1] The Colonial Defense Forces (CDF) learn that one of their top consciousness transfer scientists, Charles Boutin, has turned traitor and sparked an unprecedented alliance between three other species to wipe out humanity.

Dirac is able to posthumously neutralize Boutin by leaving a Trojan horse in a BrainPal message, oxidizing his body's smart blood and killing him.

This universe is a hostile place and these upgrades are the bare minimum the CDF can give them just to hold their own.

Jane Sagan, Harry Wilson and John Perry are the only primary characters returning from Old Man's War.