Picard is horribly worried about Worf and Riker, who are playing Mortal Kombat on the holodeck with men in rubber suits. Once they dispatch their foes, Worf, who is obviously getting a bit carried away, starts menacing Riker with an axe. Careful, he might be initiating a mating ritual! Riker manages to bring him to his senses in time for the opening credits. Was that pre-credits sequence at all relevant to the rest of the story?
Unusually, the Enterprise is actually going where no man has gone before. They've found what Wesley describes as a "hole in space" and which Data has no idea about. They foolishly go in for a closer look and launch a probe into it, which predictably disappears. As does the second probe. So they nudge a bit closer (at Wesley's suggestion, I might add) and it promptly eats them. Thanks, Wes!
Captain's log: We're screwed. Am considering spacing Wesley.
Riker comes up with a story about how in old times people thought you could sail off the end of the world. Dr Pulaski comes up to the bridge for no apparent reason other than to apparently insult Data. They somewhat optimistically set a reverse course and, of course, don't emerge from the blackness. Riker stands up the front so Picard can stare at his butt for a while.
Geordi comes up to the bridge as well, to see what the hell's going on. They drop a beacon and zoom away from it, only to find the beacon again. Castrovalva!
Then a Romulan ship decloaks and fires at them, so they shoot back and destroy it. Then another another Galaxy class starship turns up, which Riker identifies as the Enterprise's sister ship, the Yamato.
O'Brien beams Riker and Worf over, but they don't appear where they're supposed to appear. They wander around the deserted ship, hearing strange noises. When communications don't work, O'Brien tries unsuccessfully to beam them back. Meanwhile, the Enterprise switches to emergency power inexplicably. Worf and Riker discover that the internal dimensions of the Yamato are screwed up, and they can walk through one door on the bridge and arrive back on the bridge. Worf appears to be getting annoyed. Or constipated.
Outside, an opening appears which the Enterprise could escape through, but without being able to get Riker and Worf back, they can't take advantage of it. Once the rift disappears, they're able to beam the pair back before the Yamato vanishes.
Captain's log, supplemental: OMGWTFBBQ?!
They detect another rift, but it moves before they can nip through it. After a couple of times, Picard asks Troi again if she senses any intelligence at work here. Duh. A huge face appears and identifies itself as Nagilum. After there's a long and boring discussion, Nagilum kills a red-shirt and announces he wants to experiment with this whole dying thing on the rest of the crew too.
Picard responds by setting auto-destruct for twenty minutes to allow the crew time to prepare. Troi comes to Picard's quarters to tell him he might be wrong. Then Data turns up to ask about death. After a metaphysical discussion, he realises that the pair are a trick on the part of Nagilum. Then the Enterprise apparently come out of the void. Although suspicious it's an illusion, Picard cancels the auto-destruct. Nagilum appears to him on a monitor and says humans are a bit crap, really.
So the Enterprise sets course again, and Riker tells Wesley not to go near any strange holes in space. Teh end.
That was a bit crap, really. Boring, and rather transparently a bottle show to save money. Basically the only exciting bit was the pre-credits holodeck deathmatch.