"(Appropriate amount of time) ago, the United Federation of Planets made first contact with the Dominion, a hostile power. For (appropriate length of time), the Federation and Dominion have been at war, with the Federation suffering (appropriate number) of casualties. The starship Enterprise
, under the command of Jean-Luc Picard, was recalled from the front lines one week ago to engage in a top-secret mission that could determine the course of the war."
...or some such thing.
Heck, not to rip off "Emissary", but it would have been "cool" if the movie had immediately launched into the Enterprise
in the midst of a battle with Dominion ships.