Crossroad (Star Trek, Book 71)
The crew of theNautilus, a battered Starship of mysterious origin, is beamed aboard theStarship EnterpriseTM. The group claims they are freedom fighters from the future working to save the Federation from the Consilium, a group of corrupt power-seekers.TheNautiluscrew members then seize control of theU.S.S. Enterprise, and a Starship from the future arrives to arrest the renegades.  Kirk must separate his true allies from those who wish to destroy the Federation.