On the holodeck, Lt. Commander Data plays a game of poker with holographic representations of Sir Isaac Newton, Albert Einstein, and Stephen Hawking (being played by himself). Answering a question from Sir Isaac, Data explains that the game is an experiment for understanding "how three of history's greatest minds would interact" in such a setting. Just as Hawking has won another hand, a red alert is issued and Data suspends the program.
The Enterprise responds to a distress call from a Starfleet outpost. On arrival, they send down an away team consisting of Riker, Worf, Data and another security guard. They find the entire crew of the outpost dead. Suddenly they are attacked by a group of Borg. During the course of the fire fight, Riker observes that the Borg are not acting like the Borg they have encountered previously. For starters, each of them is armed with energy weapons and refer to each other as individuals. In fact, these Borg appear to be fighting more like guerrilla warriors. While fighting a drone, Data feels an emotionâangerâresulting in his breaking the neck of the drone he was fighting.
In orbit, an unidentified ship fires on the Enterprise, causing the crew to return fire. The alien ship beams up the remaining Borg from the outpost and flees with the Enterprise in pursuit. Suddenly the ship enters some kind of vortex and disappears without a trace. Back on the outpost, Riker asks Data what happened, but Data cannot explain it; he just felt angry.
Note: In the Star Trek Voyager episode "Scorpion", Seven of Nine displays a schematic of a Borg weapon - "a multikinetic neutronic mine with a five million isoton yield" - which she offers to adapt with Voyagers nanobots to fight Species 8472. The design shown on that schematic is the same as the Borg starship in this episode, leading to the speculation that the Borg Ship was a modified Borg mine.
Admiral Alynna Nechayev arrives to take command of the situation. She reprimands Picard for not destroying the Borg when he had the chance ("I, Borg") and orders him to do so if another opportunity should present itself. Meanwhile, Data is trying to understand what caused his behavior on the outpost. He tries to experience emotion again through simulations of the event, but does not succeed.
The Borg ship reappears and attacks another outpost. Again, the Enterprise is the nearest ship, which makes Picard suspicious, given that there are now several Starfleet vessels patrolling the area. The Borg ship reenters the vortex and disappears when the Enterprise intercepts; however, this time the Enterprise is caught in its wake and follows. Once on the other side, the Borg attack, beaming drones on to the bridge. After a brief fire fight, one drone is killed and another wounded, but the distraction allows the Borg ship to escape, which again is unusual Borg behavior in that they always reclaim their drones, whether alive or dead.
The crew discover that the vortex they entered is a form of conduit allowing them to travel from one star system to another almost instantaneously. However they have yet to work out how it is activated which means, for the moment, they are unable to return to Federation space. Data is sent to speak with the Borg whom the Enterprise has captured in an attempt to gather intelligence, but the drone is able to manipulate Data into releasing him, and escapes the ship in a shuttlecraft. Before the Enterprise can catch the shuttle it disappears into a conduit. However, the crew is able to learn how the conduits are activated and gives chase. They track the shuttlecraft to a planet. An away team finds no trace of Data or the Borg and something in the planet's atmosphere is blocking their sensors, so Picard decides to conduct a ground search utilising nearly the whole crew of the Enterprise. Only a skeleton crew remains on board under the command of Dr. Crusher.
During their search of the planet, Picard, Troi, a security officer and La Forge discover a building. Upon entering, they are surrounded by Borg. The security officer reacts and is instantly killed. Lore, Data's brother, appears and tells Picard that he and Data will fight the Federation. Lore has found a way to give Data emotions, and Data has turned on the Federation. Lore plans to lead these breakaway Borg to destroy all organic life; they believe that Lore and Data are perfect life forms.