During a rather uneventful period, the Enterprise picks up a T Tauri star, with a class- M planet orbiting, which is unheard-of. They go to investigate, but apparently pass through a wormhole and are knocked unconscious. When Picard and the crew revive, Data (who was immune) tells them it's been about thirty seconds. They were only thrown about a day's journey away, there are no serious injuries, and no damage, so all seems well. On Data's advice, Picard sends a probe to check out the planet in question rather than risk the wormhole again. The probe beams back images of a non-class-M planet, and Data suggests that the first reading was simply a wormhole-induced glitch. The ship goes back to its old course.

However, this neat appearance begins to unravel. Bev finds that some samples of moss she had incubating show roughly 24 hours' growth, not 30 seconds. Data, when asked, suggests a rather ridiculous hypothesis which Geordi rejects (once Picard has sent Data down to help in engineering). Picard is concerned, and orders various other checks to begin.

The checks turn up some startling results. Geordi finds that the chronometer has been tampered with, and the only two people who could have done it are him and Data. Bev finds that an ensign's circadian rhythms are way out of sync-clearly, she says, they were out longer than thirty seconds. Data cannot answer these queries, and an examination by Geordi reveals nothing physically wrong with him. Geordi then starts examining the probe, to see if it was tampered with as well.

It gets even worse. Beverly finds that Worf's wrist has been broken and reset, implying that not only has time passed, but that some or all of the crew were conscious during that time. Geordi finds that the probe simply beamed back altered library records-"stock footage" of a planet, essentially, and launches a second probe himself. When Picard challenges Data about all this, Data says he cannot answer the questions, but says his lack of cooperation is "not by choice" and implies that he's doing it to protect the crew from something worse. Finally, the second probe sends back evidence that the planet is class-M, and Picard decides to head back to that system (despite a feeling that they may face grave danger).

As they arrive, an energy field blocks their path. It sends out a small pulse, which does no damage, but takes over Troi's body. "Troi" then goes to Data, sounding very upset that "the plan has failed." Data, having just been called to the bridge, asks her to do nothing yet, saying that "it may yet be possible to salvage the situation." When he arrives, he tells Picard that they must leave immediately, but cannot explain why. Picard concludes that Data must have been ordered to conceal the truth, and eventually discovers that the order came from him, Jean- Luc Picard!

Before long, the field moves toward the ship and gets through the shields. Troi, speaking for the Paxons (a race of intense xenophobes), says that for their knowledge of the Paxons' existence, the crew and ship must be destroyed.

Data explains, via flashback, what happened: Picard talked the Paxons (again in Troi's body) out of destroying the ship by agreeing to erase all evidence of this event, including everyone's short-term memory, and ordered Data never to reveal any of it to anyone. When the Paxons claim that the plan has failed, Picard fervently suggests that it be done again-this time, taking pains to leave no clues behind. The Paxons, impressed, agree, and work commences.

Then, Picard wakes up. Data tells him that the wormhole's influence stunned them all, and that about thirty seconds have passed. He suggests that returning to that system may be unsafe, and Riker suggests a probe. Picard agrees, and issues a hazard advisory to Starfleet. Since there were few injuries and little damage, they proceed on their way........