The episode begins with Finn and Rap-Bear in a rap battle. Once Finn wins, the bear breaks down and cries. Finn comforts him by telling him that he is his hero. Finn is told by Party Pat that he thought Billy was his hero. An image of Billy in his mind possessed by the Lich sobers Finn, and he walks away.
He runs into Billy's ex, Canyon, who gives him Billy's old loincloth, which Finn wears as a cloak. Finn suggests that they should go to Billy's "crack", his treasure cave and home. Once there, after chasing away some fairies squatting there, they find Billy's bucket list in the fuel tank of Billy's motorbike. There are two unfinished items on the list. One of them is "Tell Finn that thing", which Finn remarks will bug him for the rest of his life. Finn looks at the second item, which is "Take Canyon for one last ride". The next scene shows them riding the bike through a desert, with Finn driving the oversized bike with the help of wrenches attached to the handlebars, while Canyon beats up a monster that attacks them. Finn and Canyon drive the bike over a… canyon, and bail midair. They grab a branch and watch as the motorcycle bursts into a ball of fire at the bottom. Canyon thanks Finn, and tells him they will meet again as she opens a magical portal in the river at the base of the canyon and vanishes into it. Finn unrolls Billy's bucket list and attempts to open the scroll and cross off the last line. In doing so, he unravels the scroll to the very bottom and finds another checkbox at the very bottom, saying "Lay on my back in the ocean. Just float".
In the next scene, Finn stands at the beach and tries to run into the sea, but panics and runs away again. The Fear Feaster returns and begins to harass Finn. Finn ignores it and walks down the beach to an old pier, grabs a plank and bashes himself at the edge of the pier into unconsciousness, falling into the ocean the same way he did in the earlier episode. After a trippy acid sequence where he loses his hat. He surfaces on surface of the ocean on his back. The Fear Feaster appears again and begins taunting him, but to Finns surprise his grass sword unsheathes and he slays the Fear Feaster, despite his boast that "No mortal blade can harm [him]". After that, he lays on his back in the ocean without fear. Billy appears as a talking constellation and informs him that since Finn had completed his list, he was allowed to relax in the hall of heroes, then disappears. Finn calls for Billy to wait and asks what thing he needed to tell him. Billy tells him his dad, dad the human, was alive and in "the citadel".
Tropes:
- Action Girl: Billy's ex-girlfriend, Canyon, is just as much as a butt-kicker as he was.
- Ascend to a Higher Plane of Existence: Billy does this after Finn completes the list.
- Battle Couple: Billy and Canyon were one. After Billy decided that fighting evil was pointless, they went their separate ways.
- Call-Back:
- Finn's fear of the ocean and the Fear Feaster play a big part in this episode.
- Several items on Billy's list are things that Finn himself has done in earlier episodes.
- Celestial Body: Finn's vision of Billy at the end.
- Delayed Reaction: The fact that Billy is dead doesn't hit Finn until he mentions it.
- Five Stages of Grief: Following Billy's death, Finn goes from denial straight to depression and then acceptance. Jake is still in denial.
- Jump Scare: Finn has a flashback which concludes with this
◊ reminder of Billy being possessed by The Lich at the end of the fourth season. - Losing Your Head: Finn decapitates Jordan, King of the Fairies, and chases him away when he survives it.
- Making a Splash: Canyon leaves by making a hole in a stream and walking into it.
- Oh, Crap!: Finn lets out a muffled scream and bites through his pencil when he sees the last item on Billy's bucket list will require facing his fear of the ocean.
- Piss-Take Rap: Finn and Rap Bear's rap battle. Though the crowd seems fairly impressed.
- Riddle for the Ages: How did Billy know Finn's dad was alive? No explanation is given.
- Spirit Advisor: Billy to Finn at the end.
- Tempting Fate: The Fear Feaster boasts that no regular weapon can kill it. Then Finn cuts him in half with his cursed grass sword.
- Wham Line: Billy reveals what "that thing" he wanted to tell Finn is: his biological father is still alive, and imprisoned in the Citadel.Billy: Your father, Finn. He's alive!
- Why Did It Have to Be Snakes?: Finn's reaction when Billy's final bucket list item involves swimming in the sea.
