Commander Riker is very tired when he goes onto the bridge as if he had not slept the last night. He heads down to sickbay and Dr. Crusher finds out that a bone of his right arm has changed its position a few microns, as if it had been severed and then reattached.
Commander Data makes some analysis in engineering when suddenly Geordi comes and asks him if he already has any results. Data answers that he has started just some minutes ago but Geordi says that this cannot be true. By checking his time with the computer Data realizes Geordi is right and concludes he was taken somewhere.
Riker and Data are not the only people who leave the ship as Captain Picard gets the computer to confirm two people are missing. When one comes back Dr. Crusher finds out that he is dead. In a cargo bay a hole in space appears. Dr. Crusher gives Riker an injection so that he stays awake when he is taken to somewhere again the following night.
That night Riker is taken to a laboratory where some aliens make some examinations with crew members of the Enterprise. There Riker can also see the hole in space. He escapes his restraints, shoots at the aliens and goes with another crew member back onto the Enterprise through the hole, before Data can close it.
As the rift closes something emitting energy passes through, and then escapes through the Enterprise hull, possibly a probe. At the end Picard says that this was the only way for the aliens to get into contact with human beings. Unfortunately they killed one crew member by doing it, and Riker states that they were more than just curious.