On the day of the polka concert on backstage, Applejack stayed as calm as she could until the right moment would come. The three boys were warming up on their own and she went along with it. She heard several people talking to each other while warming up on her sousaphone. When it was about time to perform on the stage at the Canterlot County Fair, she adjusted her sousaphone to a comfortable playing position, getting ready to play.

     "Ladies and gentlemen," the announcer man said over the microphone, "Introducing, the three boy and one girl polka band, 'The Polka Pack'!"

     Applejack and the Polka Pack came up to the stage, and began playing their songs they practiced. Rainbow and Pinkie were there to support Applejack and wish her good luck. Applejack was having a lot of fun playing her sousaphone until the point she saw the three boys' eyes glowing red while performing. That was not a good sign for her instincts. She kept an eye on them while she was still playing. A few hours later when she and the fake boys finished their final song, the crowd cheered and applauded until they saw the fake boys changing into the same exact creatures Applejack, Rainbow and Pinkie saw last time. The crowd screamed and ran away from the stage with extreme fear.

     The three monsters placed down the polka instruments, unplugged their ears and started trying to capture Applejack. Well good thing Applejack managed to get away from them while carrying her sousaphone with her. She hid from them for a moment to place it down at a place where she would know where to find it. Luckily, Big Mac happened to come by to look for her.

     "Big Mac, guard that sousaphone fer me while Rainbow, Pinkie and I deal with them," said Applejack as she went to face the three monsters. Her sousaphone was indeed guarded by her older brother.

     The three monsters were running toward her but they were blasted from a party cannon that belonged to Pinkie.

     "Let's get this polka fight party started!!!" Pinkie shrieked excitingly while loading it with confetti bombs again. One of the three monsters hissed at her nastily. Before she could fire, she was attacked and was thrown away, flew and then landed on the bushes. Luckily she was only covered with leaves and twigs, especially on her crazy curly hair. "I'm okay!" she hollered.

     Rainbow and Applejack were fighting against the three monsters side by side. Somehow they couldn't get the three monsters to take the injuries. Those three monsters were impossible to fight against.

     "Those guys are indestructible!" said Rainbow, "There has to be at least one weakness for us to easily defeat!"

     Then there was some music that was coming from the speakers. The three monsters stopped attacking them and started to cover their ears and shriek.

     "That's it!" exclaimed Applejack, "Music is their weakness!"

     All of the sudden, the speakers were disconnected and the three monsters stopped dancing and started to attack again. The girls were petrified and scared stiff.

      Applejack had an idea or two in mind. "At least I have a backup kind of a music," she said.

     "What's your backup music?" asked Rainbow, "Are you gonna sing or something?"

     "I dunno," said Applejack, "I won't hurt ta try." She cleared her throat and began to sing Raise This Barn, but when she sang, "Grab yer partner here we go!", she forgot that there were three monsters instead of two. She slapped her forehead with her palm and said, "Oh gosh darn it! It requires two people ta grab each other not three!" Then she sighed heavily. "I'll just get my sousaphone." With that, she went away and came back with her sousaphone.

     "AJ!" said Rainbow, "Play some other song you know and hurry! I can't fight against these freaks alone!"

     Applejack knew what other song she had in mind to play, which was Apples to the Core. She started to play the starting melody to get the three monsters' attention. The deep and dark tone of her sousaphone caused them to screech loudly. Towards the end of the song, they turned into one pile of dust.

     The crowd stopped running around and screaming and then were confused. They went over to Applejack and took a glance at the dust pile. When they realized that Applejack defeated the three monsters, they began to cheer greatly and said her name repeatedly with enthusiasm.

     "But what about the real Polka Pack?" asked Pinkie, "They're still at their houses, being held hostage!" Her hair was still covered with leaves and twigs from the bushes she fell into.

     The crowd gasped shockingly when hearing this.

     "Was it something I said?" Pinkie asked again.

     "Never mind, Pinkie!" said Rainbow, "We have to rescue those three guys before they suffer too much!"

     Applejack asked Big Mac to guard her sousaphone again while she, Pinkie and Rainbow ran from the Canterlot County Fair and went to each one of the Polka Pack's houses. They untied Buckwheat, Pinecone and Dogwood one by one, and removed the gags from their mouths. The three girls helped the three boys getting up and they all came back to the Canterlot County Fair. Applejack got her sousaphone back from Big Mac who was guarding it.

     The three boys just then noticed the dust pile.

     "What's with that dust pile?" asked Dogwood.

     "Applejack defeated those three shape shifting monsters just by playing her sousaphone," said Rainbow.

     "She did?" asked Pinecone.

     "Yep yep yep!" said Pinkie, "She sure did!"

     The boys were shocked and couldn't believe what they were hearing.

     "Anyways, they were the ones who kept you hostage," said Rainbow, "They tried to catch AJ for some reason I have no idea what it was, but like I said, she beat those freaks by playing a song she knew." She then turned to Applejack with a smile, "Do you mind playing that song again like you did in front of those shape shifting creeps?"

     "I sure don't mind at all, sugarcube," said Applejack as she did so.

     While Applejack was still playing, she noticed Applebloom coming to her, singing, "No matter what comes we will face the weather, We're Apples to the core!" That was the exact same melody Applejack was playing while her little sister was singing. At the end of the song, she played some extra notes just for fun and smiled at Applebloom.

     "I thought I heard a familiar song, but I knew it," said Applebloom, "Besides, Granny--"

     "Who's this cute lil' gal?" asked Buckwheat.

     "That's my lil' sis Applebloom," said Applejack.

     When the boys also met Big Mac and Granny Smith, they asked Granny if they could stay at their house for a visit after the concert redo. Granny approved their request to do so.