Falling Skies is always at its best when it's dealing with mild body horror — the show's original "hook" was the harnessed children, and since then the most compelling stuff has always involved humans being changed by contact with aliens. So it was nice to see a lot of that in last Sunday's episode.

Spoilers ahead...

In retrospect, where Falling Skies seemed to stumble the most at the start of this season was in moving away from the "humans taken over by alien biotech" and "Earth's environment hacked by aliens" ideas, towards a weird Nazi metaphor involving Concentration Camps and brownshirt indoctrination schools. But now, we're back to the original motif, after a few earlier hints about "skitterized" adults.

Not that this episode was all great — the clip above shows one of the cheesiest moments (where Lexi hears dueling voiceovers) as well as one of the best (where she shows off the Espheni solution to Ben and he accuses her of wanting to enslave him again. Also, some of the backstory involving Dingan Botha's family, and his freak-out in the present, wasn't as compelling as it could have been.

But still, it was gratifying to see a return to the show's core idea, and top marks for some inventive nastiness. In this episode:

1) Tom Mason and Dingan Botha get trapped under a crashed "beamer" underground, and when Tom attempts to manipulate an opening mechanism, he gets some weird alien worm creature inside his arm which has barbs that make it nearly impossible to remove. And it's growing and spreading, apparently on its way to kill him. I love the notion that controlling the alien biotechnology means letting the alien organisms invade your body. Super great stuff. And then they set off a missile and have to hide from the blast, which winds up freeing them.

Like I said, the part where the previously competent and cool Dingan suddenly loses his shit, and we hear some kind of random backstory about his son dying because of a botched swimming pool, is less awesome. Especially since it's mostly an excuse for Tom to show how cool he is in a crisis, and how good he is at talking Dingan down.

2) The clip above shows Ben visiting the Skitterization factory, where his "sister" Lexi is helping to turn humans into monsters. I'm still sad that the show has abandoned the harnessing idea altogether — even if the Espheni had some problems with harnessed kids dropping dead, there was a pretty acceptable success rate, and they got a lot of labor out of those kids first. But Lexi is somewhat more fun as a straight-up tool of evil than she was as a woo-woo cult leader. Plus the fact that she "wins" the argument over whether humans deserve freedom by hijacking Ben's spikes and turning him into her puppet again.

3) Maggie is paralyzed after the massacre in last week's episode, and the only hope for saving her is to use the alien biotech in the spikes. Which is a wonderfully creepy idea — making use of the enemy's slave harnesses as medical technology. Anne won't do the procedure unless Maggie consents — so Hal asks for Maggie's consent when she wakes up, and Maggie says no. Then Hal lies, and claims she said yes. It's great to see these characters acting more like flawed human beings, although Anne seems remarkably unfazed when she learns the truth. An injection of spike fluid doesn't help — so finally, Anne transplants a few of Ben's spike's into Maggie, giving us a nice look at the spikes' creepy tentacles as they burrow under Maggie's skin.

4) Pope and Lady Pope go out to scout the perimeter, and find one of their peeps, dead. So Pope gives him a crude cairn so the animals won't get him, and Lady Pope announces at a memorial bonfire that she won't do heavy drugs any more. This was probably the best use of Lady Pope thus far, because even as the show explores the notion of alien technology changing what it means to be human, it also has a longstanding mission to explore how war (and alien invasion) changes people as well.

As the episode ends, Tom gets out of the hole he's been stuck in, and once the beamer is exposed to moonlight it suddenly lights up. As if there's something weird going on with the moon... were-beamers, anyone?

Anyway, this was a welcome return to the show's main strengths, and the kind of imagery that made the show so fascinating in the first place. Given that colonialism does always include an element of biotech — colonists have always introduced their own crops, their own germs and their own methods of cultivation, among other things — there's a lot of territory to explore there, without getting into tired "Nazi aliens" territory. So this gives me hope.