Star Trek: Preserver by William Shatner

Paperback. Conditon: Like-New 2001. Pocket Books. 1st Edition, 1st printing.

The deadly and tyrannical Emperor Tiberius, formerly captain of the I.S.S. Enterprise, had great success turning captured alien weaponry to his advantage, but his failed attempt to sieze the tantalizing advances of the ancient First Federation has always rankled him. In the more peaceful universe of the United Federation of Planets, Tiberius sees his second chance. And a new ally will help him take it -- the counterpart for whom he has nothing but contempt, the man whose U.S.S. Enterprise™ made first contact with the First Federation: Starfleet Captain James T. Kirk.

Honorable, Idealistic, and decent, James T. Kirk is many things Tiberius is not. But he is also a man deeply in love with his wife -- and Teilani is dying. To save her life, Kirk will compromise his ideals and enter into his most dangerous alliance yet.

Battling Captain Jean-Luc Picard and a new generation of Starfleet heroes, Kirk will guide Tiberius to a long-abandoned First Federation base. There, he expects to find a source of power so great it will enable Tiberius to conquer the mirror universe -- and his own.
But on their journey Kirk will uncover long-hidden secrets about the past that raise the stakes far beyond the mere survival of Kirk's family and friends to nothing less than the continued existence of both universes.

At the heart of their quest, something else is waiting: an object from a civilization whose technology is far more advanced than any Kirk or Tiberius could expect to acquire, placed there for Kirk's eyes only by the mysterious aliens who appear to have influenced life within the galaxy over eons of time -- a message from the Perservers....