The relationship between Carter and Henry was actually my favorite part of all of it. It played out really well over the course of the season. I was really sold on it when Carter started in with the guilt trip, "You're my best friend" stuff. I was a little let down that I never got the big confrontation where Carter just shouts "I remember everything!" That being said, the scene at the end when Henry is leaving did make for a nice moment between the two of them, and wrapped that story up nicely.
One bit that I didn't think worked out as nicely was the partnering of Henry and Beverly, and the conflict that caused between Henry, Allison, and Nathan. We know now that Henry was actually out to help Kevin, but I just didn't buy his "I tried. You wouldn't listen. You didn't trust me." argument for why he went about it the way he did. Given what I know, and what Henry knows, about Allison, I have to think that just blurting out "I know how to fix your kid." is going to get you some face time.
Henry's big conspiracy did lead to the lock down, which gave Carter and Nathan bonding time and the suspense filled group following along back at SARAH with Fargo and Zane. It also laid the groundwork for the thermal cleansing, which just has to be bad. So, in that regard it worked to power the episode down the path. But I did think it was the weakest part of the plot. It just felt a little off.
As far as Kevin goes, I like the resolution. I could argue that the genetic cleansing transporter built from banned technology which I have never heard mentioned was all too convenient, but I'm willing to just roll with that revelation. It feels like Kevin and the artifact have run their course. I'm good with dropping that one for the foreseeable future, now that there is nobody left who can interface with the artifact. Of course, keeping in mind that Beverly is still out there somewhere and it hangs as a possible story somewhere in the distance.
One story that I think the writers should be running into sooner, rather than later, is the relationship between Allison and Carter. I'm not sure that the last nail was pounded into the coffin of possibility for a love connection there, but they are on that road. I don't think the secrecy and deception is going to play well with the sheriff, no matter how noble she thought her intentions were. And that look Carter shared with Nathan as they rode the panic room back up showed a new respect between the two of them. I think the good guy Carter would step aside. How it all effects the working relationship that Carter and Allison have should be interesting to see.
All things considered, it was a nice wrap-up to what has been a solid second season. It makes the recently ordered season three something to look forward to. And if nothing else, I think we all learned a valuable lesson tonight. "Boys, there's plenty of back door access for everyone."