Q appears and asks to join the Enterprise. When Picard informs him that the Enterprise crew doesn't trust him enough, Q insists that the Enterprise needs him. To illustrate, he flings them years away from any Federation starbases, where they meet the Borg. The Borg are a collective entity that captures and consumes other species and their technology. Gaigan, who turns out not to be a human, reveals that her people have encountered the Borg and faired poorly because of it. The Borg nearly destroy the Enterprise, but at the last minute, Q deigns to save them when Picard is willing to ask him for help. Picard talks with Gaigan about the future of the Federation, now that the Borg are probably coming for them.
I KNEW IT. I knew it was the Borg!
Honestly, I think this episode must have been more exciting for me than it would have been for the people first watching it without any future knowledge of Star Trek. For me, I know that we'll be seeing the Borg again. I mean, yes, they tell you that at the end of the episode, but Star Trek hasn't had the best reputation with continuity up to this point, and I knew before they even had to say it. The Borg was my favorite part of Voyager (or the only part I liked. I can't remember for sure). I am extremely pleased that this episode and the Borg reach back all the way to the first season finale. In fact, I'm going to have to start reminding myself that this particular Star Trek series is actually trying for overreaching plot and continuity. In case you weren't convinced earlier, this is no TOS. And that's coming from someone who loves TOS.
Another clue that continuity is the new in-word: Q is back! I knew he would be, from what I vaguely remembered from when TNG first aired, but I worried about how they would bring him back. Thankfully, it was plausible. It was quite apparent last time that Q pissed off some of his fellow Q people, so now we learn that they have rightfully kicked him to the curb. I enjoy the fact that he wants to join the Enterprise, but doesn't understand why they don't want him. He manages to make his point in the end, but there's also the subtle fact that he proved their point - Q is untrustworthy. He flung them at the Borg, for goodness' sake.
The one thing I'm confused about is Gainan. The other characters act like her alieness is no surprise to them, so from the viewer's perspective, it's like the writer's were winging it. I mean, 10 Forward didn't even exist when we first saw Q in season one, otherwise we would have heard about some of this silliness then. I don't mind her being powerful or knowledgeable, I suppose, but I do hate it when it feels like the writers are just throwing darts at a board. Maybe the explanation would be that Gainan joined the ship between the two seasons. Hopefully, since season two has been so much better than season one, we can look forward to less scrambling to fill in plot holes like this one.
To summarize, Borg + Q = awesome!