"Ed-n-Seek" is the 12th episode of Season 1 and the 12th episode of Ed, Edd n Eddy. In this episode, the Eds find out that the Kids are playing hide and seek, so they ask them if they can play. After a while, the kids allow this under certain conditions. The Eds then do everything they can to win.
The Eds are searching the chairs of Ed's living room hoping to find spare change, but soon get distracted when Ed finds his old copy of Slug-u-La magazine. Things get strange when Jonny and Plank come in and begin to search the room. Soon enough, Jonny receives a message from his best pal and shakes a vase. Out of the vase topples Sarah, who angrily stomps out of the room, Jonny racing ahead. Interest piqued, the Eds go outside to find out what's going on.
Outside, however, the picture is no clearer, as the Kids are running around, seemingly at random. Things take a turn for the strange when Rolf shoves his head into the ground and, when Eddy asks what he's up to, says that he is invisible. After seeing not only this but also Kevin riding his bike into a hollow tree and Jonny and Plank pretending to be fenceposts, the Eds are understandably confused. They then hear Sarah call out "Ready or not, here I come!" Understanding is instant, as they recognize the game as hide-and-seek.
They then begin to pester Sarah to allow them to play. Sarah is unwilling to do so, saying that they're in the middle of a game, so Ed finds all the kids and then asks to play. Fed up, the kids huddle together and come to a decision: the Eds can play. There's a catch, though; they have to be It.
The first try is a magnificent failure, as the kids all rush to the "home base" tree as soon as the Eds look away from it. The Eds are still it, but they have learned from this past attempt, and prove it by uprooting the tree and taking it with them in a wagon. They can't find anyone, however, and Eddy becomes fed up with this. Edd then comes up with an idea, and the trio move to Ed's garage. Edd does some work and then comes out with his new invention, Body Heat Seeking Goggles. Eddy tries them on, and is surprised that they work. Ed then asks for a turn, and upon receiving it, grins, saying that this is how the monster in "The Brainless Cyclops" found his victims.
"It" then heads out and swiftly captures the kids. The Eds have almost won, when they realize they're short one person, revealed to be Jimmy. They look around and see him sprinting for home base, which they have carelessly left behind. Ed gives chase, and Jimmy tries to work his lead for all it's worth. Unfortunately for him, Ed is faster, and manages to capture him just short of the base. The Eds then cheer and run off to hide. To this purpose, Edd has constructed another useful invention: a supply-filled fake bush. Soon enough, though, things go wrong, as the Eds begin a food fight and accidentally destroy their hideout just as Jimmy finishes his countdown and starts looking. They then desperately try to find someplace to hide, only to find that all the good places (and some bad ones) are taken. Eventually they run into Eddy's house, which happens to be the first place Jimmy checks.
The Eds are very inventive with their hiding spots, with Eddy choosing a painting, Edd a fish tank, and Ed a cartoon. Once he leaves the room they're in, however, they realize they have to make a run for it and escape the house. They run for home base and manage to make it; however, they're so pumped full of adrenaline that they hit the base way too hard and send the wagon downhill. The wagon and the tree in it hit a grove of trees, and the Eds end up buried beneath them. This is not all for their punishment, however, as Ed repeatedly rises up to make various pronouncements about how they won–each time dropping the tree on his friends as he falls back down.
Several times throughout the episode, Plank can be seen with a dimple on the left side of his mouth. Oddly, this is not part of his usual animation.
When Ed is first shown close up using the Body Heat Seeking Goggles, the strap is missing. Upon panning out, the strap is back on.
When Edd sprays Eddy with soda, the resulting drips appear to be water, even though the soda is brown.
Eddy says, "Tell me Ed, what's it like having buttered toast for a brain?" Interestingly, in "Boom Boom Out Goes the Ed," Ed's brain appears to be buttered toast. It is possible that episode referenced Eddy's comment from this episode.
When Ed pops out of his hiding place inside the television, the intertitle references A.K.A. Cartoon.
Rolf attempts to hide by sticking his head into the ground. This may be referencing the widely held, but incorrect belief that ostriches bury their heads to hide from predators.