While Apple Bloom watches, Applejack works hard, training for the upcoming Equestria Rodeo Competition being held in Canterlot. Apple Bloom is certain that her sister will wow the crowds, especially considering Applejack is a ten-time champion of the Ponyville Rodeo.
In honor of Applejack competing, the entire town prepares to send her off. And Applejack better win, considering she already promised the prize money to help fix town hall's roof, which was in poor shape even before Derpy accidentally struck it with lightning. Rainbow Dash also ends up on the receiving end of Derpy's "help," and exhorting her to just "do nothing" just leads to more destruction. Much like Oopsy from Adventures in Care-a-Lot, such is Derpy's lot.
Pinkie Pie calls for a speech from Applejack, and so the cowpony promises to make them all proud. At the train station, her friends and family give her lots of last bits of advice, though the mayor's only there to remind her to bring back the prize money. The conductor gives the last call, and so Applejack boards the train, promising to be back in a week with all the blue ribbons.
One week later, all of Applejack's friends and family are working on getting a surprise party ready in the barn in time for Applejack's return. However, the recipient of their "Surprise!" is not Applejack but a rather flattered mail pony (it was his birthday). Twilight brusquely takes the letter from him, but Pinkie Pie gives him a slice of cake. The letter is from Applejack, and simply says that she isn't coming back to Ponyville, but will send the money soon.
No one can believe such a thing. If there are three things Applejack would never abandon, it's Ponyville, her family, and Sweet Apple Acres. Her friends assume that something terrible must have happened to her, and vow to search high and low until they find her. Though as they head off, Big Macintosh and Granny Smith aren't quite as optimistic.
The other ponies ask Applejack what's she's doing there, but before she can answer, they're greeted by Cherry Jubilee, owner of the local cherry orchard and Applejack's current employer. She speaks highly of Applejack, having been impressed by all the ribbons she won at the rodeo, then heads back to give Applejack some private time with her friends. Rainbow Dash immediately jumps on Applejack for this apparent treachery to Sweet Apple Acres, but Applejack replies that she just wanted to try something different. She thanks her friends for coming, and sends them on their way. Nopony buys this, of course, and Rainbow Dash for one is not about to let all their searching be for naught. Applejack goes on the defensive, saying she didn't ask them to go searching and repeats her refusal to go home. She runs off, but the others aren't about to let her off the hook so easily.
Back at the cherry orchard, it's time for Applejack to get to work, turning the wheel that powers the cherry sorting conveyor belt. Cherry Jubilee introduces her to her new cherry sorters: the rest of the mane six! They claim that Applejack made working with cherries sound like fun, so they thought they'd give it a try. Applejack allows this on one condition: no talking about Ponyville. And they get to work. After a little while, the mane five put their plan into motion, starting with Twilight asking Applejack about Canterlot, which, not being Ponyville, is perfectly allowable. She continues on to asking about the rodeo, even though Applejack gives her nothing but taciturn answers. Rainbow Dash tries getting more out of her by fangirling over famous rodeo ponies, but this doesn't work. Even Rarity leaves the line to ask how Applejack met Cherry Jubilee, leaving only Pinkie Pie and Fluttershy at the belt.
Applejack tells them that Cherry had a stand at the rodeo, and being in similar lines of business, they got to talking. The others ask accusing questions, riling Applejack up and causing her to speed up her trotting and consequentially the conveyor belt. Rainbow Dash, Rarity, and Twilight try to find out if it was something they did while Fluttershy and Pinkie Pie try to cope with the never-ending line of cherries, until finally it's too much to handle. Applejack stops, but the momentum is such that she ends up covered in cherry goop. As the mane five clean up the cherry mess, Twilight notes that they haven't gotten anywhere, which Rainbow Dash attributes to them playing nice before. Now it's time to pull out the big guns--Pinkie Pie!
Pinkie Pie help as long as she doesn't ask any questions, which suits Pinkie just fine. Instead, she starts talking about cherrychangas, a dessert she just invented, before moving on to inherently funny words. Her incessant chattering becomes too much for Applejack to take, and once she breaks, Rainbow Dash (ears plugged) flies down to tell her they'll only call off Pinkie Pie if Applejack tells them what's really going on. Applejack refuses, so Rainbow Dash unleashes Pinkie Pie again. After a few rounds of "words that rhyme with bean" Applejack is ready to give in, but asks if she can wait until the next day. Pinkie Pie asks her to Pinkie Promise, and so Applejack does, promising to tell them everything the next day at breakfast.
The next morning, the other ponies head to Applejack's room, eager for answers. Rainbow Dash isn't so sure they'll actually get any, but Pinkie Pie reassures her that since Applejack Pinkie Promised, she'll tell all. A knock on Applejack's door, however, shows that the cowpony has already left. And Pinkie Pie goes ballastic. "Nopony breaks a Pinkie Promise!" she shouts, and races off with the others close behind. They find Applejack at the train station, waiting impatiently, and when she spots the Pinkie Pie Scorned, she hightails it out of there. In order to get away from her friends, she hires a stagecoach pulled by four ponies. Her friends, however, spot an abandoned wagon and with Rainbow Dash and Fluttershy pulling it, they take off after her. And so begins a high speed chase, pony-style!
The wagon starts to gain on the stagecoach, until a bunny hops into the road and Fluttershy brakes, sending them off course. Despite this, they manage to catch up again, and start ramming the coach to make it pull over. So Applejack tells the stagecoach team she'll pay them double if they manage to outrun her friends. But Twilight counters by saying they'll pay triple if they slow down. So Applejack ups her offer, and the stagecoach team takes off like the wind. But Pinkie refuses to let Applejack get away, and so Rainbow Dash and Fluttershy up their game and catch up yet again.
confronts Applejack about breaking her promise. Applejack points out that she didn't break her promise, since she said she'd tell them at breakfast, and she left before breakfast. She also admits that she just can't tell them what happened. Though not completely satisfied, Pinkie leaves Applejack be, falling back on the cart while asking Rarity to catch her. Not expecting this, Rarity is knocked out of the cart with Pinkie Pie. Twilight calls for them to stop and get their friends, but Rainbow Dash refuses, stating that the two knew what they were getting into. And so the chase continues.
With the stagecoach in the lead, Applejack decides to cement her lead by ignoring the railroad crossing signal and spurring the team to cross just before the train. They make it across, but the team abandons her after that little stunt. Applejack isn't worried, figuring the train will buy her enough time to get away, until she spots the pegasi-pulled wagon soaring over the train. Even so, Applejack refuses to give up, and starts to run again, but this time she's easily caught by Rainbow Dash. Their collision reveals the secret Applejack had been trying to hide, though it isn't exactly apparent to her friends. All they see is a ton of prize ribbons that were in her bag, and they're pretty impressed. But Applejack points out that not one of them is for first prize, meaning she didn't win any money. Which is why she was working at Cherry Jubilee's orchard, since she couldn't face Ponyville without any money, not after that sendoff.
But the others assure her that they don't care what place she came in, money or not, she's still their friend. Applejack points out that she promised the mayor the money to fix town hall's roof, and she doesn't think she'll be as forgiving. Fluttershy assures her they'll find a way to fix the roof, but without her, "we'd never be able to fix the hole in our hearts," a sentiment that even touches Rainbow Dash.
And so Applejack comes home and writes her letter to Princess Celestia, about how you can't run from your problems. Meanwhile, Rarity and Pinkie Pie also make their way home, working a handcart. While Pinkie natters on, Rarity swears that Rainbow Dash will pay.
There's been quite a bit of controversy over Derpy becoming an actual voiced and named character. To be honest, I mostly saw her (as I noted earlier) as channeling Oopsy from Adventures in Care-a-Lot, right down to the voice. In fact, if the director hadn't revealed that it was actually Tabitha St. Germain doing her voice, I would have bet real money that it was Ashleigh Ball "reprising" her role.
Apple Family Dog Pile!