Ok, so here's the plot as I see it: (prepare for wild speculation based on nothing)
In the familiar TNG era there is the Spock we all know, gettin on in years, when suddenly BAM! Fanboy paradox! Spock discovers a secret Romulan plot, even more dastardly than creating teenage Picard clones!
A Canon-altering way-back machine, designed specifically to erase THE SHAT from the canon time-stream. He calls up his good friend, Captain Riker of the USS TITAN, and is taken to DS9, where, after a birthday party for Sisko in Quark's bar, they use the Orb of Time to travel back, intent on fixing the canon time stream.
They of course do this with the Defiant. They need the cloak and all to keep from screwing things up worse. They are now in the past, yet everything is changed! Canon has been thrown out of whack, and it's up to Spock to save the day - he is the only one familiar with the time period. He uses the Orb to search Iowa, then SF Academy. Finally he finds the Romulan spy trying to weld an exploding tribble to the hull of the Enterprise.
Sulu whips out his sword.
Everyone shares a light 'closing joke' on the Bridge. Probably at Chekov's expense.
They decide, fuck it, this new version of canon is pretty kick-ass, so let's just leave it this way. Party at Tom Cruise's house with Captain Pakistan.