Adventure Time’s “Islands” miniseries tackles American self-absorption – but for kids!

Every Sunday, we pick a new episode of the week. It could be good. It could be bad. It will always be interesting. You can read the archives here. The episode of the week for January 29 through February 4 is “Islands,” a miniseries that is part of the eighth season of Cartoon Network’s Adventure Time.

The longer Adventure Time runs and the closer it gets to its series finale (which will air at the end of the show’s ninth season, at some point in 2018), the sadder it gets.

Cartoon Network’s candy-colored, elaborate fantasy for kids (and, okay, everybody else too) has always had a deeply melancholic streak. In reviewing its 2015 miniseries “Stakes,” I dubbed it the best coming-of-age story of its era, and coming-of-age stories always embrace the twinge of sadness that comes from the things you need to give up to become the person you are.

In many ways, it reminds me of the Harry Potter books — starting out fresh and fun and whimsical, with only hints of darkness, but gradually growing weightier as its characters come to realize the importance of things like duty, responsibility, and honor.

But that melancholy has become one of the show’s dominant tones in its last few seasons, and it bubbles over in the eight-episode miniseries “Islands,” which finally reveals much of the series’ backstory, including the parentage of its foundling main character, Finn. One of the episodes ends on a lengthy, beautiful shot of Finn’s mother staring out at softly lapping ocean waves she believes have just claimed her husband and son, and it’s the saddest thing I’ve seen on TV in ages.

J.R.R. Tolkien, the father of modern fantasy, created his world of Middleearth as, essentially, a hoped-for past. Yeah, it was full of as much corruption and darkness as human endeavors usually are, but it was also home to the Hobbit-happy Shire, as beautiful and pastoral a fantasy land as you could imagine.

That streak of nostalgia and longing for an imagined past infuses lots of fantasy. It’s not always overtly present — particularly in contemporary works like George R.R. Martin’s Song of Ice and Fire series — but even those darker tales have a sense, somewhere in their DNA, of a world that has gone wrong and can be set right with the right leader or system of government or something.

So in that sense, Adventure Time’s growing melancholy is in keeping with its main genre. Sure, it might seem weird to blend that restless sadness with a show where a significant number of characters are literally made out of magical candy, but there’s a reason Adventure Time’s somber elements don’t feel like they come out of nowhere.

But the show simultaneously occupies another genre that has a more direct tie to nostalgia: post-apocalyptic fiction. This happened largely accidentally. The show was straight fantasy until a first-season episode introduced an iceberg full of frozen 21st-century businessmen to the world — which meant Adventure Time’s universe had been, at one time, our universe, which de facto made the series post-apocalyptic.

Over time, that post-apocalyptic element has slowly stretched its tendrils into every aspect of the series. Finn, for a time, seems to be the final human alive. Vampire Marceline, immortal, has memories of being a little (human) girl in the aftermath of nuclear war, before she became a vampire. The series’ original antagonist, the Ice King, has a similar backstory: He was a human in the post-nuclear wasteland, until he found a magical crown and gradually became the magical being he is when the series begins.

Post-apocalyptic fiction carries with it the implicit, constant reminder that at some point, things went wrong, and those things that went wrong might have overlapped with our time period. It functions as a simultaneous warning (don’t have a nuclear war!) and nostalgic longing for a time before, when things were better and maybe less complicated (something pretty much anybody older than the age of 13 can relate to).

These two genres have bought Adventure Time plenty of space to accommodate its growing melancholic streak (along with its growing sense of being an ad hoc epic). But they’ve also brought it room to function as a strangely timely warning signal.

“Islands” sends Finn and a few other characters (notably Susan Strong, one of the show’s handful of other humans) on a quest to find the last remaining human beings, who are on an island far across the sea. On the way, they encounter sea monsters, bizarre security measures, and an eerie society that seems to have permanently uploaded itself into a virtual-reality playground. (The VR segment and an earlier season eight episode mark the first Adventure Time installments written and storyboarded by the series’ creator, Pendleton Ward, since 2014.)

The miniseries feels appropriately momentous. Finn is going to learn the truth about his parentage, and Susan is going to find out where she came from. And the central question of what happened to humankind, period, has hung over the series from its very first season.

Finn and Susan aren’t the last humans. (How could they be?). But what remains of humanity lives in a relative utopia — either a digital playground or what looks like your standard gentrified neighborhood — ignoring the strange dystopias all around them.

To be sure, Ooo, where Finn and his pals live, isn’t a traditional dystopia. It’s still a pretty neat place to hang out (like Tolkien’s Shire), but it’s routinely threatened by dark monsters and evil spirits. The remaining humans, secure in their safe cocoons, don’t really need to care about such things.

Yet “Islands” also shows the ways the remaining humans aren’t as safe as they’d hope. Those stuck in the virtual world are emaciated and cut off from anything real, while those in the “real” world were devastated by a plague. Seemingly the only person trying to keep that real world up and running is Finn’s mom, Minerva (voiced, beautifully, by Sharon Horgan), who has uploaded her consciousness to the virtual world, the better to occupy an endless series of robots who can be there to help someone at a moment’s notice.

But Minerva’s obsession with security (which developed in the wake of losing her husband and son) means she’s unable to see that Finn still needs to help his friends back in Ooo. As soon as mother and son are reunited, he’s making plans to leave, and she’s making plans to keep him by her side, in poisoned comfort, forever and ever and ever. The message is clear: You can help your own community, and you should. But that sometimes means you’re ignoring worse things happening one island or one continent over.

I don’t mean to suggest “Islands” is some sort of sophisticated critique of American self-absorption (though it’s at least a nuanced one). But the series’ commitment to understanding that Finn’s growth as a person and character means him sometimes making very difficult choices — to leave home, to leave friends, to leave parents both adopted and biological — makes it feel at once braver and more bracing than most other shows on television.

Increasingly, Adventure Time feels like a quiet landmark, an embrace of the idea that maturity means more than hitting a certain age. It means looking out for others before you look out for yourself.

Adventure Time airs new episodes sporadically on Cartoon Network, and you should probably check the network’s listings. Its previous seasons are available on Hulu and Cartoon Network’s website.

Correction: Finn’s mother is named Minerva, not Miranda.