Man-Kzin Wars 12(2009)

Larry Niven

The kzin, formerly invincible conquerors of all they encountered, had a hard time dealing with their ignominious defeat by the leaf-eating humans. Some secretly hatched schemes for a rematch, others concentrated on gathering power within the kzin hierarchy, and some shamefully cooperated with the contemptible humans, though often for hidden motives. In war and in uneasy peace, kzin and humans continue their adventures, as told by Paul Chafe, Hal Colebatch, and Michael Joseph Harrington, expanding on the concepts created by New York Times best-selling writer Larry Niven.
A human secret agent and her hired kzin companion infiltrate a planet newly occupied by the kzin, and discover that humans were on the planet before the dawn of space travel, and claim to be part of the Roman Empire. Where did they come from - and can they survive the inevitable kzin attack?
A man wakes up with over a month's gap in his memory. He remembers being hired by a mysterious woman for a job with the condition that his memory would be scrubbed afterward. Obviously, the scrub worked, but now the police suspect him of murdering the missing woman. And a kzin is threatening him with much worse than anything the police would do.
The Protectors - powerful ancestors of the human race who live only to guard it and destroy all its enemies - have learned that the kzin have discovered a rich cache of anti-matter in deep space. One Protector brings a human out of stasis-sleep and enlists his involuntary help in her desperate mission to stop the kzin from gaining this source of unimaginable power.