"Memory" is the title of the eleventh book in Lois McMaster Bujold's Vorkosigan series, and is best read after the preceding two books, Brothers in Arms and Mirror Dance.
In the beginning, Miles Vorkosigan goes into combat while still suffering from the after-effects of being killed and revived in the previous book. As a result, he suffers an epileptic seizure and injures friendly personnel. He tries to conceal this by falsifying his mission report, but he is caught lying by Simon Illyan, head of Imperial Security, and forced to resign from ImpSec.
Soon afterwards, Illyan's implanted memory chip which gives him a photographic memory begins malfunctioning, and Miles suspects that a plot to destroy Illyan's career and subvert ImpSec is in the making. His attempts to investigate this are blocked by Illyan's deputy, who appears to suspect him of the crime, so he asks Emperor Gregor Vorbarra to assign an Imperial Auditor to the case to give him the necessary authority. Gregor instead decides to give Miles himself a temporary Auditor's appointment; after Miles successfully resolves the crisis, this is made permanent.