Been watching a lo-o-o-ot of episodic tv, including Falling Skies.
Aliens invade, zap nearly everyone, and those few left alive look to be goners unless they organize a resistance. The Second Massachusetts is formed, an irregular militia who take their name from a regiment in the American Revolutionary War. In terms of story, the first 2 or so seasons remains a family drama with American War of Independence themes. The 2nd Mass faces Mechs (large lethal robots) and skitters (eight-legged alien foot soldiers) and such horrors as the harness, a parasitic device that render a human subject to skitter control and thus enslaved.
Now, this is all good. As tv, it's old school, largely wholesome and serious, and raised up by the central performance of Noah Wyle. Then at some point - finally - the show shifts. They start telling World War 2 stories. All the while retaining this family-centric focus, they shift rapidly through all the American war back-catalogue and by Season 5 they've become a sci-fi horror show with Overlords on the back foot, ancient aliens flitting about, and the continuing threat of skitterised humans. They've even been to the Moon. There's a weird lack of affect a lot of times. Stuff happens that should be accompanied by wailing and rending of garments, but characters just shrug it off. And other times, they dip right into psychosis. All of which is great. They do retain the family-as-god theme of the original show, which is probably a fixed point the show will never escape. All to the good, I suppose. Don't abandon your roots. In all, it's meta-fantastic! Strong, weird, compelling performances persist, and the art direction is spot-on. They sometimes even - just every so often - they let the characters express how odd every storyline has become too. And I don't mean to mock. This show has mutated in a way that episodic tv shows don't often survive. They retain their core and yet have become something different. It's astounding.
As of yesterday I'm all caught up. Season 5, I'm happy to note, is moving into Walking Dead territory as well. Things can only get better.