Finn and Jake finally reunite for one more adventure.
SUMMARY (Spoilers!!!!!!)
Finn the Human (Jeremy Shada) dreams of himself and Jake the Dog (John DiMaggio) escaping from the Ice King (Tom Kenny) and saving Turtle Princess and Lumpy Space Princess (Steve Little and Pendleton Ward). The dream ends with Finn at Jake’s grave, realizing that Jake died decades ago. When he awakens, he discovers that he’s now old (and voiced by David Bradley) and his dream was due to a brain parasite. Finn discovers that he’s actually dead of old age and that he is now in the land of the dead. Finn, now younger again, decides to journey through the afterlife to find Jake. He meets with one of New Death’s (Chris Fleming) minions, which turns out to be Tiffany (Aryan Simhadri). Tiffany reveals that New Death is trying to change the afterlife and that Jake is in the 50th Deadworld. Finn steals a harmonica from Tiffany and uses it to travel the afterlife, eventually finding Joshua, Margaret, and Jermaine (Kent Osborne, Maria Bamford, Tom Scharpling). They inform him that the 50th Deadworld is a place that can only be reached by people who don’t want to get there, a kind of Nirvana. Tiffany arrives and, under New Death’s orders, blows up the Deadworld where Joshua, Margaret, and Jermaine live, but Finn manages to find enough peace to enter the 50th Deadworld and find a zen Jake, who no longer remembers him.

Finn gets attacked by New Death’s minions, finally bringing Jake back to normal. New Death reveals this was part of his plan and destroys the 50th Deadworld, dropping everyone into the 1st Deadworld, a hellish prison. Finn and Jake contact Peppermint Butler (Steve Little), who puts them in touch with Life (Corinne Kempa), New Death’s mother. Upset at what her son has done and his interruption of the cycle of reincarnation, she gives them the kiss of Life, a staff that can kill New Death. Finn and Jake manage to face New Death and trap him, only for it to be revealed that he killed Death (Miguel Ferrer, R.I.P.) under the influence of the Lich (Ron Perlman). The Lich plans to destroy the afterlife and end all life, but Mr. Fox (Thomas Herpich) grabs the kiss of Life and ends New Death, becoming the New New Death. Finn goes to be reincarnated and, while Jake originally decides to stay in Nirvana, realizes he wants to spend another life with Finn. The two head off to be reborn together.

END SUMMARY
I don’t know how to review this episode other than to say that I have never had to pause an episode of Adventure Time to brace myself emotionally before. It is obvious in the beginning of the episode that the events are a dream, but I still wasn’t ready for an entire episode of this show to start off with the revelation that the main characters are dead. The show even drives it home by having a second title card saying “FINN AND JAKE ARE DEAD.” I realize that Adventure Time frequently referenced a very elaborate afterlife (with Finn and Jake even making plans to meet up and this episode featuring Finn’s signal), but you still don’t expect a show that was ostensibly for kids in the beginning to just say “yep, they’re dead. Also, Jake’s been dead for decades and Finn was alone.” That’s dark even for this show.

The show finally, seemingly for the ultimate time, manages to get rid of the Lich. Finn, who was born from the same comet that the Lich was, has basically always been implied to be its ultimate adversary (even more than Billy). The idea that the Lich hand (which is apparently the last real Lich since Sweetpea redeemed him) could exist even beyond death is something that has been suggested by a number of people since its last appearance in the show. This appears to finally end that discussion: The Lich is now perma-dead. It won’t come back to threaten Ooo. Technically, there might be a Lich hand in every dimension now, but we don’t really need to think about that. I think it’s appropriate that the last act of Finn before coming back as a new incarnation is to destroy him for good.

This episode is all about closure, but also about the fact that loss is not the same as closure. The world keeps moving even when we lose things, but things are never really lost. Finn lived most of his life without Jake, but never was able to forget about him, because Jake was a piece of Finn. He was his brother, his friend, and his partner in adventuring. And that’s how it is when we lose someone. We lose a piece of ourselves, but we also keep a piece of them with us, because we are more than just ourselves, we are shaped by all of the people in our lives and so we carry them on with us. Whether reincarnation is real or not, a piece of us always goes down the line through the people we know and the people they know and so on.

Possibly the best moment of this episode, though, is the very end. Finn admits that when Jake died, he always kept waiting to see him again. Because of this, Finn wants another chance to live a life that can get him to nirvana. Jake wishes him well, but then Jake jumps in after him saying that it’s great being alive with Finn. Despite the fact that Jake had found true inner peace, supposedly the highest calling of any life form, he wanted to spend another life with Finn. The deepest kind of love may not be the one you’d die for, but the one you’d live for, and that’s what we see here.

Overall, just a fantastic episode. It’s weird that it’s not the last one, but I think we all know it’s the real finale.