Voyager arrives at a desolate moon and makes preparations to drop off the Borg. As they do so, those same Borg begin an attempt to seize control of Voyager, as the war is going badly, accelerating their timetable. The drones access deflector control, using the dish to open a quantum singularity, but also alerting the crew to their activities. True to his word, Chakotay decompresses the cargo bay, killing every drone save one: Seven of Nine. There is nothing they can do about the singularity, though, which draws them and deposits them in a strange environment filled with fluidic matter. Seven hails the bridge and informs Chakotay that they are in a realm known as fluidic space, the home of Species 8472. Seven informs them that their presence has been detected and provides an oddly precise timeframe for the arrival of a bioship.
Chakotay notes that precision, and after some prodding Seven acknowledges that they Borg have been to fluidic space before. In fact, it was those incursions (and the spectacular failure of their attempts to assimilate Species 8472) that started the war in the first place. Seven adds that her link to the Collective is weak in fluidic space, rendering her unable to call for help. That being the case, she renews her insistence upon completing and deploying the nanoprobe torpedoes.
As they argue, the Doctor calls Chakotay to sickbay. There, he finds Janeway, on her feet and livid. The Doctor filled her in on everything she missed, and she wastes no time in chewing Chakotay out, accusing him of having taken the first opportunity to disregard her orders. He protests, informing her of Seven’s revelations about the Borg’s role in starting the war and urges her to disable Seven and use the deflector to return to normal space. Janeway, however, is determined to reinstate the alliance with the Borg. Chakotay gets heated, reminding her that the Borg cannot be trusted and citing his own experience with the Cooperative. The tension deescalates when Janeway gives voice to the fact that their only hope is to stop fighting each other. Soon after, Janeway returns to the bridge, where she tells Seven that Chakotay has been confined to the brig and orders Tuvok to assist the drone in preparing the torpedoes. The hope is that if the weapon works, 8472’s sense of self-preservation will lead them to withdraw to fluidic space.
Two hours later, Voyager is bracing for battle. The nanoprobe weapons are ready, and a number of Borg modifications have been made to the ship in the hope of giving them a fighting chance. Right on schedules, four bioships approach. Kes’s visions begin again, though her attempts to communicate fall on deaf ears. The bioships begin their attack, and Voyager returns fire with a spread of modified torpedoes that do… nothing. At first. After a brief delay, the bioship crystalizes and explodes.
Their point made, Janeway orders Seven to open a singularity and return them to the Delta Quadrant, which she does. Upon emerging in normal space, they are set upon by more Species 8472 bioships. As before, the torpedoes make short work of them and the survivors retreat to fluidic space. With the battle won, Janeway addresses Seven, calling on the Borg to fulfill their part of the bargain. The Borg, of course, do what they were always going to do and double cross Janeway. As Seven seizes control of the helm and alerts the Borg to their location, Janeway signals Chakotay, who is revealed to have been in the cargo bay the whole time. As he stands in one of the Borg regeneration alcoves, the Doctor attaches a neuro-tranceiver to Chakotay’s neck, linking his mind to Seven’s. The link won’t last long, but it’s enough for Chakotay to access distract Seven, accessing her human memories and even calling her by her original name: Annika. As the link fails, Torres uses it to send a power surge into Seven’s implants, severing her link to the collective and rendering her unconscious.
With control restored, they put as much distance between them and Borg space as possible. Later, Janeway and Chakotay mend fences and Janeway wonders aloud how much of Seven’s human self still exists under all that Borg technology. Chakotay reminds her that Seven was assimilated at a very young age, but Janeway correctly points out that they’re responsible for whatever happens to her now. As the two head for the bridge, the now-former drone lies in sickbay, her skin already losing its Borg pallor…