All Fall Down is the tenth of the first season along with the episode Under Duck which comes before it. All Fall Down first aired on April 23 of 2004 and is written by Kathy Waugh with its storyboard by Greg Hill.
The title card depicts Peep, with half a chestnut shell on his head, walking down a grassy path while looking upward to the right and left. On a dull pale orange coloured background, located at the top, is the words “All Fall Down” in large text. “All Fall” is in dull green text with “Down” being placed underneath it, slanted horizontally to the right, and in orange text. Beneath “All Fall Down”, in the same fashion and in small black text, is “Written by Kathy Waugh” over top of “Storyboard by Greg Hill”.
Set in fall, Peep, Chirp, and Quack have chance meeting with Squeak who tells of how soon the sky and everything else will be falling. While speculating about this, the three friends become convinced that it is true with Peep setting out for an explanation. After meeting Newton and learning that the turtle has never seen the sky fall down, Peep is able to influence his friends that the world is safe.
The episode opens by showing two skinny branches extending from a high section of a tree, the fall coloured leaves on them wavering in the breeze, and a pale blue sky in the background. Peep, Chirp, and Quack are playing joyfully in a leaf pile, when suddenly Peep hears a high-pitched muttering coming from beneath it and discovers Squeak, under her brick, waiting to be “rescued” from the leaves. After the three birds, upon Peep's request, remove the leaves from Squeak's house, the mouse mentions to Peep, after a short conversation about leaves, that it would be wise for him to stay in his can before “things get worse”. Upon Chirp's further questioning, Squeak reveals that she believes soon everything will be falling down, as evidence from various other things falling, including everything skyward, before disappearing from view beneath her brick.
Later, the three birds speculate on what Squeak has said and suddenly objects start falling down around them, prompting them to run to a safe place. The birds stumble across a red balloon, which Quack uses to indicate Squeak was wrong but, as the balloon bursts on a tree branch, the three quickly run to their homes. Chirp and Quack later turn up at Peep's can, as Peep is the only one with a roof, and attempt to force themselves into it, despite Peep stating that their past attempts failed. Deducing the situation as silly, Peep leaves to proves that the world is safe and dons half the shell of a chestnut. Peep bumps into Newton and their conversation results in Newton telling that he has never seen any part of the sky fall down in all his years. Peep ponders Newton's conversation all the way back to his home, and finds Chirp and Quack, still in his can, uncomfortably squished.
Before Peep can explain what Newton told him and the reason why he has concluded the world is safe, Chirp cries out for help to get out of the chicken's home. Peep rolls his home to the edge of a ditch and then pushes it downwards, with the resulting speed and sudden collision with a rock sending the can into the air and freeing both birds. Upon Chirp's asking, Peep explains all that Newton told him to eventually convince his friends that nothing skyward will fall down while other things may. The three birds roll Peep's can back to its original location and rest, with Quack's mentioning Squeak again prompting the chicken to go and find her to tell her what they have learned. Peep find's Squeak in a clump of grass a short distance from his home and, upon further questioning, is told by the mouse about her worrying tendencies as she nibbles on a nut before she tells of the horrors of winter. The episode ends with Squeak scampering off and Chirp questioning what winter is as a breeze blows a pile of leaves that covers the three friends.