| Season 4, Episode 5|
|Airdate:||April 30, 2012|
| Written &|
| Rebecca Sugar|
"Light My Fire"
"Highway to Hell"
When Princess Bubblegum is struck by lightning, Finn & Fionna take her in. But while Finn is being a good samaritan, the Nut Kingdom closes in on a strategic position.
It is a stormy night. In fact, it's a severe thunderstorm. Lightning is crackling all around. A sudden boom of thunder wakes Fionna (who is hatless). Finn (also hatless) is also woken up. Jake & Cake are still fast asleep. Both Finn & Fionna attempt to go back to sleep, but the thunder keeps them awake. It also scares them. A boom near the Tree Fort is enough to frighten Fionna. She climbs out of her bunk, goes to Finn & asks him she can sleep with him. Finn is not hesitant to oblige.
Soon, they are so scared, they start to hold each other in fear. It seems to work...until they hear a scream coming from outside. They are quick to respond. When trying to look out the window, visibility is practically nothing, thanks to the heavy, heavy rain. Finn gets his raincoat & heads outside, but can't find anyone. He heads back inside to get a flashlight from the Weapons Depot.
Back outside, he finds a figure face-down on the ground, apparently smoking. Getting closer, he finds a completely blackened Princess Bubblegum. Finn rushes back to the house, he tells Fionna about the situation, and that they must get PB inside at once. Fionna doesn't even bother to get her coat, so they share the same coat. Once they get her, the winds start getting much more intense. Finn shouts that the storm will drop a tornado any moment. They quickly get PB inside, wrapped in a blanket & on the couch. Finn fetches a thermometer & sticks it in PB's mouth. Meanwhile, Fionna sends an emergency code on Cake's radio to all outposts, bases & allied installations.
Finn finds that PB's temperature is topping out at 105 degrees, a fever! The phone rings on that note. Peppermint Butler worriedly asks where PB is. After explaining the situation & hanging up, Finn & Fionna head back upstairs.
The next morning, there is not a cloud in the sky. Finn is the first to wake up. He heads downstairs to check on PB, and finds she is still asleep. Finn heads into the kitchen for a glass of OJ. Soon enough, PB wakes up. She is confused as to why she is on Finn & Fionna's couch. She tries to stand, but finds she can't stand, let alone even sit up.
Finn hears her groans & immediately rushes to her. PB is happy to see Finn. He then goes to the kitchen to get her some breakfast. Every morning, Finn likes to see which piece of toast pops up first. But it's always a tie. This morning's no different. Finn also gets a glass of milk. After buttering up the toast, he puts a bendy straw in the milk & places them on a tray. PB happily eats the toast while Finn tells her what happened the night before (in detail, going as far as to include the part about him & Fionna cuddling due to the thunder). When Finn finishes, Fionna comes down the stairs. Finn & Fionna greet each other & discuss PB's condition. Suddenly, the phone rings. The voice asks if his refrigerator is running. Finn answers that it is running efficiently, then interrogates the voice. Another voice in the background gives away the identity: General Pistachio. Finn makes a very serious-sounding threat, then hangs up.
Over the next several days, Finn nurses PB back to health. But one day, Cake gets the message on the radio: the Nut Kingdom is closing in on a vital oil field. Without it, many vehicles in the Candy Kingdom's arsenal will be immobilized! Finn can't bring himself to leave a still sick PB alone, so Fionna goes it alone.
At the oil field, the Nut Kingdom wastes no time in sneaking in, knowing their cover has been blown by codebreakers. Fionna leads the charge against the enemy.
The battle is heated, but the Candy Kingdom manages to hold the line. All of a sudden, a Nut Soldier with a heavy build and wielding two greatswords appears. Many, many Candy Soldiers and even a few humvees are taken out in a blink of the eye. Fionna prepares for the duel, but is unsure whether she can win without Finn.
Back at Outpost Alpha, an SOS comes in over the radio: Fionna is pinned down and close to death. Finn is torn between saving his twin or tending to his girlfriend. PB then stands up, assuring Finn she is fine. Finn and PB then set off for the front.
At the oil field, Fionna has been driven back by the Swordsman. Neither bullets, tank shells, or rockets do anything. With her back to the wall, Fionna is resigned to death...until she hears Finn's war cry, followed by one from PB.
Finn enters with his sword drawn, and drives the Swordsman back with a flurry of attacks. PB has on her person a Steel Sword, drawn and ready. A three-on-one duel begins.
In the end, after a bloody duel, the heroes emerge victorious when the Swordsman is shoved into the jet engine of a Nut Kingdom B-52, causing a massive explosion. The rest of the enemy army retreats immediately.
Back at the Candy Kingdom, Finn is made a 3-star general. PB thanks Finn for taking care of her over the past several days, and the two kiss as the episode ends.
- Finn: Jeremy Shada
- Fionna: Ashley Johnson
- Princess Bubblegum: Isabella Acres
- Cake: Roz Ryan
- Peppermint Butler: Steven Little
- Swordsman of Nuts: Gary Schwartz
- General Pistachio: R. Lee Ermey
- Additional Voices: Tom Kenny, Dee Bradley Baker, Frank Welker, Pendleton Ward, Steven Blum
- The Nut Swordsman is based on the German Mechanic character from Raiders of the Lost Ark, right down to his death. His voice, on the other hand, is based on the Heavy class from Team Fortress 2 (Gary Schwartz was even brought in to do the voice).
- First time Princess Bubblegum is shown swordfighting, which would eventually become a staple of her character.