The Raven's logs (beginning at Stardate 32623.5) indicate that Seven's parents, the Hansens, had received authorisation from Starfleet to enter the Delta Quadrant on a mission to study the Borg up close. Seven, then a young child named Annika, was with her parents on the Raven. Excerpts of the logs show that the Hansens were almost fanatical about their research on the Borg, taking great risks and becoming more and more confident with each successful mission. For example, they developed a shielding for the Raven that allowed them to virtually fly in formation with a cube ship without being detected and a bio-mask to allow them to transport into a cube - again without being detected by the Borg. They even kidnapped drones from their regeneration cubicles, studied them in detail aboard the Raven and then returned them before their regeneration cycles were completed. In this way, they amassed a great deal of knowledge about the Borg without much thought or concern for their safety or the safety of their young daughter. With information gained from the Raven's logs, Janeway and company device a careful plan and then run simulation after simulation to get it down right. Two away teams will beam into the Borg sphere. Tuvok and Kim will locate and plant explosives on the spheres shield generators. Meanwhile, Janeway and Seven will locate the sphere's transwarp coil and transmit its exact coordinates back to Voyager to it can be transported away. For everything to go right, the away teams must beam in, do their tasks and beam out within a couple minutes or the sphere's intruder alarms will be activated.
Everything is ready for Operation Fort Knox to proceed the next morning but unknown to anyone Seven is contacted by the Borg Queen - who is aboard the sphere. She knows about Janeway's plan but makes Seven an offer she can't refuse -- if Seven will surrender herself to the Borg, they will let Voyager continue on its way unharmed. The Borg Queen explains to Seven that she wants Seven because she is unique. Seven does not reveal this to Janeway and Operation Fort Knox begins as planned. An unmanned shuttlecraft rigged to give off life signs is sent out as a decoy while the two away teams beam into the sphere. With copies of the bio-masks developed by the Hansens, Janeway, Seven, Tuvok, and Kim are ignored by the drones that go about their Borg duties. Everything seems to be going according to plan up to the point where the away teams are to be transported back to Voyager. Seven gets a transmission through her cortical implant from the Borg Queen and Seven announces to Captain Janeway that she plans to stay with the Borg. With several Borg cubes now converging on Voyager, Janeway doesn't have the luxury of trying to talk sense into Seven and the three remaining away team members beam back to Voyager and depart the area at full warp. Seven is led by several drones to a large room where the Borg Queen's head and shoulders are attached to a mechanical body and she welcomes Seven home.
Using the transwarp coil taken from the Borg sphere, Voyager eventually locates and travels deep into Borg territory using the type of shielding developed by the Hansens. Inside, the Queen is trying to convince Seven of her rightful place among the Borg and makes it known that her intent is to use the enhanced nanites that Doc used to un-assimilate Seven in a plan to infect Earth with Borg nanites which, after a period of years, would result in assimilation of all life on the planet. As part of the reintegration of Seven into the collective without actually re-assimilating her, the Queen assigns Seven to assist in the assimilation of a newly encountered species of over 390,000 individuals. The experience, however, is very difficult emotionally on Seven and she actually helps a small group of captives to escape. By now, Janeway, Tuvok, Doc and Paris are in the Delta Flyer on a mission to rescue Seven. Janeway is beamed into the Borg ship and a stand off almost immediately arises between the Queen -- who has drones ready to assimilate the stubborn Seven -- and Janeway, who has an enhanced phaser rifles trained on the Queen.
Meanwhile, the Delta Flyer is preparing to fire a spread of enhanced photon torpedoes at the small Borg ship. With this distraction, Seven and Janeway are beamed away and the Delta Flyer goes to transwarp speed away from Borg space. However, hot on their tail is the Queen's sphere. As the Delta Flyer emerges from the transwarp envelope, Voyager fires a spread of photon torpedoes that collapses it, destroying the Queen's sphere. Now safely away from the Borg, Captain Janeway records in her log that Voyager was able to travel 20,000 light years closer to home before the Borg transwarp coil failed. She also notes that from her recent reconnection with the collective, Seven has accumulated a vast amount of knowledge about the Borg, which she has downloaded to Voyager's computers. In a private conversation afterwards, Seven tells Janeway that, although the Borg Queen believed that Seven was unique and of great importance, she did not expect Captain Janeway to risk Voyager's safety to try to rescue her…
For a start, just how did two civilian exo-biologists rate getting their hands on state-of-the-art military technology in the form of that obviously Federation-issue ship? Two problems immediately arise with the given stardate of 32776 or whatever it specifically was: this is *ten* years before the first contact between the Enterprise and the Borg in system J-25 and six to eight years before Starfleet allowed families and children to accompany their ships' personnel. How is it that these two practically have encyclopedia-level knowledge of the Borg before first contact and how is it that the Borg we see are the more advanced First Contact-model Borg instead of the earlier BOBW-model? Janeway and Seven can beam out the Borg transwarp coil out of the engineering core of the Borg sphere but somehow they can't beam themselves out at the same time? What is this drivel about having to get back to the beam-in point? Voyager's transporters suddenly no longer have the capability to handle cargo and people? With the Borg's shields down, the Voyager's transporters can't lock on to two humans, one human/Borg hybrid and one Vulcan from anywhere in that sphere? The sensors suddenly aren't good enough to identify their own crew or their combadge signals? Time is of the essence in the sabotage/theft mission, yet Janeway and Co. stroll casually through the corridors of the Borg scoutship instead of running or at least jogging? What is the point of Tuvok telling Harry where to place the charges on the shield generator thingy and Harry waiting for the instructions before doing anything? He didn't learn his job during the rehearsals on the Holodeck?
The Borg recaptures Seven because the Queen wants her distinctive nature to serve the Borg by her remaining as she is yet throughout her time with the Borg, Seven is *constantly* being told by BorgDom that she should discard those very human qualities the Borg seemingly find so important to advance their plans? f humans are so difficult to assimilate, why bother sending one cube every few years, rather than sending a hundred cubes to Earth, which certainly would be enough to overwhelm any resistance - which is the way they're supposed to operate in the first place? BorgDom rattles off the weaknesses and disadvantages of humanity - if we're that worthless, what is the purpose in assimilating us? What advantage does it give them? If the Borg have this ability to infiltrate tailored nanoprobes to infest a target world and bring about the slow but eventual assimilation of a species (which actually is a clever idea and one which would be difficult if not impossible to combat) why don't they simply adopt this method to assimilate all their target species? Just capture a few individuals of each species, alter the nanoprobes and voila - it's just a matter of time before you've got a new phalanx of drones. No waste of resources, no losses from combat, no resistance - plus you get the people and the world intact. So why not adopt this method for all assimilations? This would pretty much make the Borg unbeatable - a couple of millennia and the Galaxy is theirs. Or are the Borg simply impatient? Or too dumb to work out the obvious conclusion?
In the end, there simply are too many things, which just don't make sense from any standpoint. Dark Frontier wasn't offensively awful but it was sure a waste of time and in the end we're more or less left right where we were to begin with. The ship's still lost in space, Janeway and her incompetent bunch survive and the Borg degenerate even further. They may as well not even have bothered.