Sky Douglas Conway

Captains Uhura and Chekov make a visit to a newly comissioned replica of the Enterprise on which they served years ago, only to wind up revisiting the Guardian (which they first encountered in "City on the Edge of Forever") and a strange man who throws a monkey wrench into not only their past, but everyone else's.

It is nearly ten years after Voyager's return from the Delta Quadrant, and the Federation is in a crisis. The Federation's main suppliers of dilithium crystals are disappearing. Space and time have folded around several planets, effectively isolating them from any contact with outside worlds. And this phenomenon is not natural - someone or something is causing this to happen. This necessitates drastic measures; some of which are outside the Federation's normal jurisdiction. (imdb)