Escape from the Citadel

"Escape from the Citadel" is the second episode in the sixth season of Adventure Time. It is the one hundred and fifty-eighth episode overall.

Synopsis
Finn and Jake follow the Lich to the Citadel, where Finn meets his long lost dad. But just how far does the apple fall from the tree?

Plot
Finn and Jake hitch a ride on a Citadel Guardian after he imprisons and transports The Lich to the Citadel. Upon arrival, the Guardian attaches The Lich's crystal prison onto a much larger crystal "cell block." Finn and Jake then look around for Finn's long-lost father, whom Finn initially suggests might be a Guardian. Jake points out a strange looking "old kid" who resembles Finn, and it turns out to be Finn's father incarcerated inside a crystal jail cell. They then notice that the Lich's cell is excreting a gray slime that is beginning to infect the other prisoners and Guardians. The Lich's influence over the citadel enables a massive jailbreak. One of the prisoners is a void caster, who has the power to open portals, so he uses his power to attack a guardian by opening a void in front of a train that Starchie is driving in the Candy Kingdom, which crashes into a guardian. As gray slime fire forms on Finn's father's cell, Finn uses Jake as a flail to free his father, who introduces himself as Martin. Martin is reluctant to answer either Finn nor Jake's questions about his motives for abandoning Finn. Jake begins to encourage Finn to leave his father behind, calling him a loser. Martin notes that the fighting will cease once the last Guardian dies. He then points out that the last Guardian is currently sinking into a gray swamp. The Guardian shoots a beam that hits Martin in the lower right shin, which obliterates all the flesh from a segment of his leg. Martin tells Finn that the blood of a Guardian contains healing properties. Finn and Jake retrieve the regenerative guardian blood and put it on Martin's leg, which is quickly restored to a healthy state. The Lich then entrances Finn, telling him that only death will be imminent for all life and that he is all alone in the world now. Jake then appears unconscious next to Finn. Finn wakes up and calls for Martin, who had fled with the other prisoners, abandoning Finn once again. Finn feebly attempts to strike the Lich as he encroaches. His attack was ineffective, but there was some guardian blood left on his hand from healing his father's wounded leg, which causes the Lich to scream as flesh begins to grows on his bones. Finn then throws more guardian blood onto The Lich, restoring more flesh around his chest. Finn then tells Jake to finish him off while he chases after his father. Martin and the other prisoners cut a stem connecting a floating bit of the citadel to the ground, and at Martin's request, the fugitive void caster creates a void to escape into, which begins to suck the floating chunk of land upward. Finn grabs the two halves of the severed stem, preventing his father from leaving, but he struggles to hold on. Jake tells Finn to let it go, but Finn refuses and the Grass Sword takes over Finn's right arm, allowing him one last tremendous pull. Finn's arm gives out and is severed and Martin says "Wait, what about air" really fast right before escaping through the portal. Finn falls into the water below where a small piece of Guardian blood touches his arm, making the stump of an arm sprout a flower. Jake pulls Finn to shore where Shelby is revealed to have been hiding out the entire time. Finn is reminded of the Lich and asks Jake if he finished him off. Jake says there's no need, as the Guardian blood transformed the Lich into a baby-like creature, rendering him seemingly harmless. Finn, Jake, Shelby, and the infant Lich return to the Candy Kingdom by way of the portal that Starchie drove through during the battle. Later, Tree Trunks and Mr. Pig are sitting in her house when outside Finn and Jake's chatter can be heard. The doorbell rings, interrupting a somber Tree Trunks saying, "I think we should get a d-". The couple sees outside their door an infant Lich in a stereotypical abandoned-baby basket. Tree Trunks looks excited and implies that this sudden addition to their family has changed her feeling about whatever she was about to say.

Main characters

 * Finn
 * Jake
 * The Lich
 * Martin
 * Citadel Guardian

Minor characters

 * Snail
 * Starchie
 * Shelby
 * Tree Trunks
 * Mr. Pig
 * Void caster

Trivia

 * Starchie is in the title card riding a form of a 4-2-0 steam locomotive.
 * Tree Trunks wanted to divorce Mr. Pig until they got their baby "delivered."
 * It is unknown if Martin survived after the events of this episode since on the chunk of crystal, he, along with the Ancients, were left floating in space without air.

Cultural references

 * The transformation and mutation of the Grass Sword as it consumes Finn's arm is similar to the awakening power of Tetsuo from the 1988 Japanese animated film .

Episode connections

 * Finn losing his right arm to the Grass Sword fulfills Finn's destiny to lose his arm, as multiple alternate versions of Finn have been seen with an artificial arm:
 * On the future Crystal in the Dungeon Train
 * His vision of himself in "Mortal Folly"
 * His "mirror reflection" in "King Worm"
 * His Farmworld counterpart in "Finn the Human" and "Jake the Dog"
 * A robotic pillow arm in "Puhoy"
 * One of his previous lives, Shoko, as revealed in "The Vault"
 * There is a reference to the episode "Apple Wedding," where Tree Trunks is revealed to have many ex husbands, when Tree Trunks is about to divorce Mr. Pig.

Errors

 * When Finn states that they don't have a Star Skipper, the grass sword is missing. It later returns after the scene switches between Martin's reaction.
 * After the scene when Martin gets his leg zapped, Finn is seen without his grass sword in one scene where he repeats "uh-oh."
 * In the scene where the Lich is seen upside-down inside his crystal, Billy's eye looks like it normally should. However, at the end of the previous episode, Billy's eye was wide open when he was frozen with the Lich in the crystal.
 * When the Lich breaks free from the crystal, he appears to have all traces of Billy's skin removed. But in the next scene, he has some of Billy's face still attached to him before it slides off.
 * Although the Guardians' blood can heal apparently any wound, it doesn't heal the Lich's broken right horn.
 * It's unknown if this is an error or not, as the blood can only heal if there is a trace of its previous existence. This is why the blood didn't heal Finn's arm.
 * In the scene where Finn is climbing after Martin on the floating rock, his grass sword is also missing in the shot before the creature cuts the cord Finn is climbing.
 * While Martin is climbing, his boot that was struck and ripped is fixed.