Weee, Borg attack! Holy crap, Voyager's actually using the beam-a-torpedo-on-board tactic! Unfortunately they didn't actually want to destroy the ship.
They beam some of the debris on board and salvage. The HoloDoc is happy because he's found a Borg medical arm, while Seven and Torres fiddle with a transwarp coil. Ah, it was Harry's idea to beam the torpedo over.
They check the tactical data they retrieved and locate a badly-damaged Borg sphere. Janeway wants to steal from transwarp coils from it. She has data from Seven's parents ship and wants Seven to study them.
[Flashback mode on!] Annaka's father tells her they're going to go study the Borg. Then later on, her parents are on the Raven zoooming around. This all, of course, contradicts the fact that Star Fleet wasn't aware of the Borg until Q Who, and since DS9 and TNG are contemporary, and Voyager by virtue of the Maquis, is... oh, they've detected a Borg cube. The cube scans them, then pisses off. They follow at distance. [/flashback mode]
Voyager catches up with the sphere, which is still badly damaged. They run a simulation which results in the Borg beaming on board Voyager. They decide to work on it. Janeway has concerns about how Seven will handle being on the Borg ship.
The Borg communicate with Seven and tell her if she rejoins the Borg, they'll spare Voyager.
Seven finds a log entry where Annaka's dad is wandering about on a Borg cube using a "bio-dampener". HoloDoc sets about working on some for the mission.
Janeway is a coffee pusher. Bwahahaha! She tries to reassign Seven to the bridge for the mission - Seven thinks the mission will fail and talks her out of it.
The mission starts off without a hitch, but Seven decides to stay on board and is cut off from the other. The Borg move to attack Voyager. Janeway, Tuvok and Kim beam off and the sphere transwarps off back to Borg space, where Seven meets with the quick-assemble Borg Queen.
[END OF PART 1. WOOOOOOOOOOOOOOO!]
Borg Queen claims the Borg put Seven on Voyager as an experiment.
Meanwhile, Torres is hooking the transwarp coil up to Voyager. Janeway is pissed at Torres for accessing Seven't personal logs for info. Neelix appears to be in charge of destroying left over Borg debris. Naomi goes to Janeway with a proposed rescue operation to retrieve Seven. Janeway's found the comm signals from when the Borg were signalling Seven earlier...
Back at Borg Central, the Queen tells Seven that they're not going to reassimilate her. They want Seven to help them assimilate humanity. They set out to do some assimilating in a Borg diamond. Sexy.
[FLASHBACK] The Hansons are tagging Borg to keep track of them. They're excited because one of the Borg is from unimatrix 1 and may have hung around with the Queen. [/FLASHBACK]
The Voyager crew work on a plan to rescue Seven. The first part apparently involves a team transwarping along in the Flyer.
Meanwhile, Seven helps the Borg in an attack on a planet. Hearing the cries of people being assimilated and encountering it first-hand disturbs her greatly, and she helps four people escape. She confronts the Queen again, who is aware of Seven's deceit.
The Flyer comes up on Borg Central. The Queen is planning an assimilation bomb that they intend to use on Earth and wants Seven's help. She shows Seven her drone Dad. That'd make a good comedy show... Meanwhile, Janeway and Tuvok beam on board and wander around with bio-dampeners. Are Borg blind then? Sheesh.
The Borg manage to lock on to the Flyer. Janeway turns up and confronts the Borg Queen. Seven helps Janeway make a getaway, and the Flyer transwarps out, pursued by the Borg diamond. They reach Voyager who uses photon torpedos to collapse the conduit, which spits out a crapload of Borg debris.
Voyager uses the transwarp coil for a while before it gives out (what? they couldn't replicate another one?? Shame they didn't steal two.), and Janeway has a discussion with Seven on stuff and so on. Teh end.