The Enterprise, with Riker in command, goes to answer a Romulan distress call claiming engine failure, but keeps shields up and red alert ready just in case. In the meantime, Picard is returning from a conference, along with Troi, Geordi, and Data. They pass the time discussing various facets of the conference, but Troi suddenly finds that from her point of view, everyone else has suddenly frozen!

They "unfreeze" in a few seconds, but all are mystified about what it is Troi could have seen. As Data and Geordi run a diagnostic, Troi tells Picard about the situation - and then finds that everyone is huddled around her seeming very concerned. This time, she is the one that froze - and did so for a full three minutes. What's more, Geordi's readings suggest that she didn't age during those minutes either - as if time simply stopped for her.

Still unable to contact the Enterprise, they increase speed. However, just at that moment, the starboard nacelle inexplicably fails. They stabilize their flight, but find that the nacelle's readings indicate continuous operation for almost 50 days. Puzzled, Picard goes to check the fuel logs, but finds that the bowl of fruit previously on the table is now full of very rotting fruit. He reaches for the fruit, and suddenly screams in pain.

Troi and company arrive, concerned, and find that Picard's hand has aged at more than fifty times its normal rate while he was near the bowl. The tricorder detects a bubble of temporal instability within which time runs at about fifty times normal speed - and the bubble includes the starboard nacelle of the runabout, thus explaining the engine failure. They attempt to move away from the bubble, but find themselves backing into another - in fact, the sensors now detect a whole host of these pockets, varying in shape, size, and effect. It appears that the space- time continuum has been "shattered" in this area, and the trail of breakage leads to the place where they're supposed to rendezvous with the Enterprise. They head for it as quickly as possible, while taking pains to avoid any of the pockets.

When they eventually reach the Enterprise, they are stunned to see it frozen in time. It sits, dead in space - with a Romulan Warbird near it, also frozen, and firing on the Enterprise. The Enterprise shows damage, while the warbird does not, prompting Geordi to suggest a surprise attack. There is also a second beam going from the Enterprise to the warbird's engineering section, which no one can explain.

They decide to go aboard the Enterprise, and after Geordi and Data work up a skintight force- field to let them enter a different timeframe without being integrated into it, all but Geordi go aboard. First, on the bridge, they find three Romulans, all with disruptors. One sits at Con, and another is standing over a helpless Riker. Picard and company discover that they can move objects, but decide not to try to change the situation until they discover more about it. Based on the data readings existing on the screens (which they can't change), Picard heads for transporter room 3, Data for engineering, and Troi for sickbay.

In sickbay, Troi finds several Romulans, and the usual complement of sickbay personnel. The Federation officers are all staring in shock at something, and Troi turns to see that it is Beverly, being hit point-blank by Romulan disruptor fire. She quickly heads for Picard, but in doing so brushes a female Romulan, who begins to move...

Picard, in the transporter room, finds three Romulans being beamed aboard by Worf. These Romulans, however, have no weapons - and one even appears injured. As the mystery deepens, and Troi tells Picard that Beverly can't survive once time begins to run smoothly again, Data calls them both to Engineering.

There, he shows them the cause of strange readings they saw on the bridge: the warp core is in the process of exploding. What's more, since the explosion occurs so rapidly, Data can now tell that time is not stopped dead, but merely slowed down to an infinitesimally slow rate. He estimates that the explosion will destroy the Enterprise in just over nine hours. The cause is unknown, but is in all probability related to a power transfer currently going on between the two ships, which is the second beam they'd seen earlier. The analysis is cut short, however, when Picard begins to snap from the strain, alternately laughing hysterically and crying for help.

Geordi brings them back, and finds that the protective fields aren't quite as good as he hoped - Picard was in a state of "temporal narcosis", in effect drugged by the conflict between the two timeframes. Modification isn't possible, so their only choice is to continue and keep visits to one or the other ship short. With Picard staying behind this time, the team goes to the warbird's engine room.

There, Data, Geordi, and Troi see signs pointing to a Romulan evacuation, not an attack. The core breach on the Enterprise is traced to feedback on the power transfer beam, which the Romulans were apparently trying to stop. With the signs pointing away from a Romulan attack, they look at the Romulan engine core, which is reading as stopped. They find a maelstrom, still moving, which is a strong break in the space-time continuum, like the ones they'd found before, only more than a million times as powerful. There are also several dark specks seen in the core, which register as organic and possibly alive!

The core, hit with a great deal of energy from the tricorder, suddenly flashes - and time begins moving again. The team sees the Romulans doing their level best to sever contact with the Enterprise and prevent the core breach - except for one Romulan they do not see, who sees them and quickly heads for the shadows. The attempt is unsuccessful, and Picard sees the Enterprise explode - except that immediately following that, time flows backwards, back to the point where they first saw it.

With time frozen again, the team continues exploring the engine room as they speculate on the cause of the sudden change in time. Geordi, however, is attacked by the one Romulan from the shadows, who is still able to move. Both are knocked unconscious, and Geordi is put into severe shock. Unable to save him, Troi removes his force-field, thus "freezing" him in the hopes that he can be saved later. The Romulan is alive, but Data's scans show that he may well not be a Romulan...

Data, Troi, and the prisoner return to the runabout, where the tricorder data is analyzed. The structure of the "specks" is similar to that of the alien they've taken hostage, though far simpler, and Picard theorizes that they are embryonic forms of the alien they see. That alien wakes, and tells them some of what they need to know. He "assumed" the Romulan body in order to exist in this timeframe, and had come to save their young. This species, it is discovered, nests its young in singularities such as black holes. The Romulan engine core uses an artificially created singularity which they thought would suffice, but instead the nest's presence shut the engine down. The alien stops there, but Picard continues: The Enterprise came to help them restore the engine, and the power transfer endangered the nest, which created the feedback that destroyed/destroys/will destroy the Enterprise. That act also disrupted the space- time continuum, causing the problems they've encountered so far. The aliens did their best to attack the Enterprise to save their young. The prisoner goes so far as to say that there is one other adult around, but dies before he can say more.

Shortly thereafter, Picard suggests altering the tricorder and then using it on the engine core again. With luck, it can be altered so that time will flow backwards first, then forwards - and if it goes back far enough, the power transfer might be preventable. As Data works on it, Picard and Troi plan where to be and what to do, as they are likely to have very little time.

Everything is made ready: Picard is on the bridge, Data in Engineering, and Troi in sickbay. Data remotely activates the tricorder, and time begins to flow backwards. As things flow backwards, however, Data is attacked by the second alien (the "Romulan" seen earlier in sickbay) and incapacitated temporarily. He recovers quickly, but not in time to stop the transfer. He places a containment field around the warp core and hopes...

Meanwhile, Picard sees the Romulans helping on the bridge, including one Romulan reaching down to help Riker up from a fall. Picard orders a very surprised Riker to continue evacuating the Romulans, and to get Geordi from the engine room as well.

Troi pushes Beverly out of the way as the Romulan fires, then holds the Romulan at bay. He and Beverly, however, explain that he was firing at the alien and that she only got in the way - "and where did she go?"

Data tells Picard that the transfer is still underway and that feedback is imminent. Picard remotely guides the runabout into the path of the power transfer, disrupting the beam. The Enterprise is saved, but the warbird vanishes into a different timeframe, along with the aliens. Everything is back to normal, although Riker is very confused. "It's going to take a little time to explain, Number One..."