got it while typing the post in 'Enterprise'.
Basically this is my idea for a DS9/Voy movie (Yes, both.)
Voyager is docked at Deep Space 9, preparing for a long exploration mission in the Gamma Quadrant. Chakotay is now captain, and onboard for the start of it, Colonel Kira Nerys. a few faces aren't there though from the Voy crew, aside from Janeway whom Chakotay has a chat with over subspace. Mention is made of the missing crew members, whom Chakotay wishes where with them, but those didn't want another long period of being outside of the federation (i.e. bad experiences in Delta quadrant got to them. or something.) Voy crew left: Tom Paris, and B'Elanna Paris, Tuvok (who is now the XO) and Seven, who now goes by her birth name, Annika Hansen. Since she isn't starfleet, She and Chakotay can continue their relationship. (Note: I haven't seen all of season 7 - even that episode where they began one. I have seen endgame but it has been too long to remember beyond the upgrades and that bit in the future with harry commanding the rhode island and so on.) Kira catches a few close moments, and it reminds her of Odo, in a way. The parellels... you know. Anyway. They set off, and Kira gives them the 'guided tour' so to speak. Voyager meets up with another starfleet vessel returning from a much shorter exploratory mission. It's going to head back in after resupply.
Skip ahead a few weeks. Voyager receives a distress signal, and heading to the source, discovers that ship, adrift in space, completely lifeless. little to no sign of attack. Soon, they recieve another... and another. no sign of battle damage.. no forced entry thing, no ion trails and such to speak of for other ships in the area, escape pods all accounted for, all shuttles, computer logs intact up til the point of the ship loosing power. (The antimatter containment issue would be pointed out and become a plot mystery in of itself since, loss of power would be loss of containment and boom). Loss of power - no way to escape through transporters etcetera and so on.
it all points to that the ship just suddenly lost it's antimatter and other fuel sources - completely and so quickly that the computers didn't detect it - indeed, scans reveal that the ships (all of them), have no sources of fuel withwhich to generate power.
say the 6th they come across, in enviro suits, they beam onboard a Jem'Hadar battleships - one of the big'uns that the Valiant tried to take on. same thing except, where in the other ships, personal effects and *food* stores and such weren't taken, the ketracel for the Jem'Hads has been taken. And Odo materialises from the wall when the obviously starfleet guys make a pass through important areas of the ship.
Odo needs medical attention though - whatever happened, his memories are fragmented (naturally, for a mystery) and something about the ship without enviromental support sent his shapeshifting stuff haywire.
Hows that for a beginning?