Star Trek: Mission's End — Ty Templeton

"The most important ""lost"" tale of the Star Trek saga can now be told: The final mission of the original Starship Enterprise and her crew. What prompts Mr. Spock and Doctor McCoy to retire from Starfleet? What earns Kirk his promotion to Admiral? And what is the mystery of Archenar-IV that threatens to tear the Federation itself apart? All will be revealed in this collection of the five-issue mini-series, with appearances by fan-favorite characters."