- Back at Headquarters, Disgust and Anger wander in to see why they're awake again so soon. They find Fear cowering under the control panel in, well, fear.
- Ticked off because he can't even get a good night's sleep anymore, Anger decides it's time to put the running away idea into Riley's head, and he feeds a lightbulb into the control panel. It's done.
- Riley looks up bus tickets online. Anger decides that they'll steal money from Mom's purse to pay for the ticket. After all, it was her and Dad who got them into this mess in the first place—or at least that's how Anger rationalizes stealing dough from Mom.
- On the train headed for HQ, Joy tells Sadness that her idea to scare Riley awake was really good, and that she's not so bad after all. Sadness is honored.
- They also pull out one of Riley's memories and reminisce about the good old days. They watch Riley celebrate with her parents and hockey teammates by a big tree.
- Joy remembers how happy Riley was in that moment, surrounded by her loved ones. Sadness is happy, too—because the team lost, and Riley missed the winning shot, felt awful, and wanted to quit hockey.
- Joy says they'll keep working on the whole "immediately focusing on the worst stuff part" when they get back to HQ.
- Riley creeps down the stairs and sees her mom on the phone, trying to clear things up with the movers. When her mom walks into the kitchen, Riley goes into her purse and snags her credit card.
- Honesty Island crumbles, taking the Train of Thought's track with it. The Train of Thought derails and disappears into the Memory Dump. Joy, Sadness, and Bing Bong are stuck once more.
- One of the Mind Workers tells Joy that Riley's running away.
- Back at HQ, Fear isn't sure running away is such a good idea. Anger insists that is. Riley was happy in Minnesota; if they want her to be happy again, she should go back to Minnesota.
- Joy decides the best way back to Headquarters is through Family Island, but then it starts crumbling, too. Chunks of Long-Term Memory start falling, as well. It's chaos.
- Just then, Joy sees a memory get pulled up a recall tube bound for HQ. That's it. They'll get recalled.
- Joy gets in the recall tube. Sadness tries to get in with her, but Joy won't let her for fear that she'll taint the Core Memories with sadness.
- The tube whisks Joy up and away, leaving Sadness and Bing Bong behind.
- As more and more sections of Long-Term Memory start to crack and fall, one ruptures the recall tube. Joy falls back down—and into the Memory Dump. Bing Bong falls in, too.
- The Memory Dump is piled high with thousands and thousands of fading memories. Joy tries to scramble to the top, but it's no use.
- Bing Bong tells her there's no point in trying climb out of there; they're stuck, and everybody's going to forget about them.
- Joy collapses to the ground and sifts through the Core Memories.
- She sees the sad memory of Riley crying in front of her classmates on the first day of school.
- Then she picks up a trio of happy memories from when Riley was much younger. Then she comes back to the sad, recent memory again and breaks down in tears. (Real ones, not candy.)
- After Joy has a good cry, she picks up the hockey memory ball that they'd looked at on the train: The one where Riley and her parents and hockey teammates are all celebrating by a big tree.
- She brushes the surface, rewinding it a bit, and it turns blue.
- She sees Riley sitting in the tree by herself, feeling down, and Joy hears Sadness's words in her head again: "It was the day the Prairie Dogs lost the big playoff game. Riley missed the winning shot. She felt awful. She wanted to quit."
- It dawns on Joy that Riley's parents and teammates were only there in the happy memory because Riley was feeling sad. In other words, it was Riley's initial sadness that ultimately created the happy memory that followed.
- Joy's determination to get to HQ is reinvigorated. Bing Bong tells her again that they're stuck in the Memory Dump forever. According to him, they might as well be on another planet.
- This gives Joy an idea. She starts singing Bing Bong's song about being an imaginary friend.
- Bing Bong joins in, and they use it to locate Bing Bong's rocket ship—you know, the one he was going to use to fly Riley to the moon—amidst the piles of faded memories in the dark (and thoroughly depressing) Memory Dump.
- Joy and Bing Bong pile into the rocket ship and take off down a big pile of memories, trying to use the momentum to catapult themselves out of the Memory Dump and onto the Long-Term Memory cliff above.
- They try and fail, try and fail. Joy's just about to give up for good when Bing Bong says they should try again. He's got a good feeling about this one.
- Just as they're about to make their ascent out of the Memory Dump, Bing Bong—unbeknownst to Joy—bails, lightening the load in the rocket ship. Joy makes it to the cliff above and lands safely.
- Joy realizes that Bing Bong sacrificed himself and is stuck in the Memory Dump, probably forever.
- He celebrates because Joy made it, and tells her to take Riley to the moon for him. Then he fades away.
- No, we're not crying. We just have some Frito dust in our eyes. Yeah, that's it. Frito dust. Chili cheese. The extra tear-producing kind.