13 Years Later, 'Adventure Time's Scariest Episode Is Still a 10-Minute Masterpiece

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Don't believe me? Do yourself a favor and watch the greatest (and scariest) episode of Adventure Time in the show's 10-year run: “Simon & Marcy.”

You could go into “Simon & Marcy” totally blind (it's season 5, episode 14; streaming now on Hulu, Disney Plus, and HBO Max) and come away a weepy mess. But to understand what really makes this story so great, we have to go back to the beginning.

The Ice King has been around in Adventure Time since the very start. He appears in the original viral animated short that launched the show, and shows up again in the cartoon's third official episode. For the first few seasons, Ice King's deal was pretty straightforward: he'd hang out in his mountain lair with his penguin henchmen, kidnap princesses using his icy superpowers, and get his butt kicked by series protagonists Finn and Jake. Then, in season 4, everything changed.

Something had always been a little off about the Ice King, but in season 4 episode 25, "Remember Me," we got our first clue why. The story follows the Ice King as he visits Marceline (the vampire queen) and asks for help writing a song to attract princesses. Marceline seems frustrated by Ice King for not remembering a shared past that the audience is also unaware of. Then, out of nowhere, she refers to him for the first time by his real name: Simon. That alone was a bombshell, but a year later, Adventure Time dropped an even bigger one.

Simon & Marcy

Aside from a brief opening scene where the characters play a pickup game of basketball, "Simon & Marcy" is told as one big flashback set 996 years before the events of Adventure Time. In the immediate aftermath of the Mushroom War (the nuclear conflict that transformed the Earth as we know it into the radioactive, fantasy land known as Ooo), two figures trek through an apocalyptic cityscape: a middle-aged man named Simon and a young girl called Marcy.

It's unclear how exactly they know each other, but the pair appear to be the last two humans left on Earth (or at least in this decimated city). In place of other people, the world is full of zombie-like green mutants with neon ooze pouring out of every orifice. Simon only has one weapon to fight back against the "Oozers," a magic crown he keeps fastened to his belt. When placed on his head, the crown gives him the power to control the ice and snow, but it also saps him of his sanity. (Singing the Cheers song seems to help keep him grounded, but only a little.) In just 10 minutes, "Simon & Marcy" manages to be scary, funny, and beautiful — sometimes all at once.

In an article for Entertainment Weekly ranking their 14 favorite episodes, the Adventure Time creative team placed it at number 7, writing:

We described this as The Road "except for kids" when we pitched this episode to the network. There was a lot of back-and-forth before we could get it approved. But it was worth it to find a way to make the Cheers theme even sadder.

That just about nails it. Adventure Time always excelled at hopping between genres. One week it was a fantasy adventure. Another might be an epic space opera, or an existential stage play. So it's no huge surprise that when the show's creators decided to tell a post-apocalyptic drama, they also stuck the landing.

What is surprising is just how important "Simon & Marcy" turned out to be to the larger Adventure Time mythos. This could have been a great one-off story that solved a mystery set up one season earlier. Instead, it unspooled into even more stories about both the Ice King and Marceline that would play out over nearly 300 episodes of television — and a streaming spinoff that's still running today.

"Simon & Marcy" might just be the most important episode in Adventure Time history. The real treat is that it also manages to be one of the scariest entries. I'd like to see Tony Soprano do that.