At first episodes seem to have no connection at all, but if you follow with attention you see they are actually CONNECTED.

The catch here is that the episodes are in reverse order. There are hints here and there to this. But if we watch from Episode 8 back to Episode 1 it makes more sense.
Also Episode 8 is the longest and provides the story, and the others are shorter and no story is explictly told, but they build up on each other.

Taking into account the details I will point out bellow, I think Goedam is a work of a GENIUS, and that is why I liked it so much.
Made me curious enough to see if my theories are right.

But in order to point out those awesome details I need to explain what happens in each episode.


** SPOILERS **

Episode 8: Birth

It starts with the tale of Yeommae hex. We find out that shamans abduct children, starve them and kill them to capture and use their spirit.
We can see then how the shaman kills a child.
Afterwards we see a customer whose husbands has and affair, and she wants him dead so they won't divorce. The shaman gives her a talisman to be put in the pillow case.
- Director spends here a lot of time focusing on her jewelries, especially on her ring, showing her (or her husband's) wealth. This is strongly connected to Episode 7.
Then we see a mother asking the shaman to find her child. Her child must be the one that shaman killed at the beginning of the episode and whose feet were buried near a tree, as in the end we see the mother hanged above her child's feet.
But before that, we see the birth of a monster baby.
The talisman plays important role both in Episode 8 and Episode 7.

Episode 7: Threshold

It starts with a boy tripping. He is going with his mother to visit his grandmother.
The woman tells her husband not to take off the talisman from bedroom wall because it brings bad luck. Also informs him a boy and a cop went missing.
While being home alone the man steps on hair, and after pulling the hair out he hears a scream.
After he comes back home he takes down the talisman and a monster appears while he sleeps.
The monster looks like being made from cut pieces (like the feet from Episode 8), and also looks like a grown up version of the child born in Episode 8.
Some important details here are:
- The monster was there even though the house was "protected" by talismans (at least 2 shown, one above each door) .
- In the house you can see the child's and wife's items, like toys and make-up, but no items belonging to the man. There are also no wedding photos. It gives a feeling that he doesn't belong there.
- There is also only one bedroom and only one bed.
- The woman has a cross, a gold necklace, showing man is wealthy enough, but no other jewelries, not even a wedding ring. Why would she wear the cross, but not the wedding ring? Also if her faith in Christianity is so strong, why would she need talismans?
Maybe the reason for all these is that the man is the husband of the woman from Episode 8. We know for sure the woman from Episode 8 wants him dead, before they divorce, but what if the apparent wife from Episode 7 works with her to kill the man? A talisman like the one from Episode 8 might be hidden in the house.


Episode 6: Dimension

We see a video from an elevator where a boy lies down scared by something. However, the police found a dead body that is too deteriorated to belong to the boy and also the clothes are different.
Then, the detective in charge finds that the boy posted online about interdimensional travel.
While going up and down according to the list posted by the boy, the detective sees himself and then a woman appears out of nowhere.
The woman asks him to press number 1, but the elevator goes down without stopping. Afterwards, she kills him. However, she does not appear on camera.
When the police finds the body again it looks much worse, but they can conclude that the clothes look identical to the detective's clothes.
At the end we see 2 girls getting in the elevator. But if you pay attention you notice that the 2 girls are actually the girls from Episode 4, Min-yeong and Se-hui.
Here, Se-hui is scared something might go wrong, while Min-yeong is the more curious one, mocking her friend for being so scared.

Episode 5: Red Shoes

In the classroom 3-2 students talk about Jin-gyeong that jumped in front of a truck, having her lower body crushed.
The teacher then comes in and tell them not to tell anything to police and not feel guilty (because they bullied her). She also wants o make sure everyone deleted the evidence of bullying.
The teacher asks then for class rep to draw attention of her colleagues. The class rep is Ji-ye KIM that appears in Episode 1.
The one but last that leaves the classroom is Seo-hui PARK that also appears in Episode 1.
We can see that at this point in time both Seo-hui and Ji-ye are alive and well.
The only one left in classroom is Hye-su SHIN.
At 9 PM the teacher receives a messages from Hye-su asking her to come to classroom to talk something about Jin-gyeong. (75% battery left)
When the teacher gets in class she finds Jin-gyeong upper body that complains that Hye-su lower body didn't fit and asks the teacher to borrow her legs.

Episode 4: Curiosity

We see the 2 friends, Min-yeong and Se-hui, that got in elevator in Episode 6 watching a video from CAM 6 (this is a REFERENCE to Episode 6) in which a monster appears.
Se-hui is sure the video is a hoax, while Min-yeong gets scared and wants to go after their books.
Knowing Min-yeong gets easily scared, Se-hui already prepared a prank on her and stops between floors 2 and 3. On wall it appears at 3/2. Remember about classroom 3-2? And she asks Min-yeong to bring her books too.
In her friend's cabinet Min-yeong sees the scary doll.
After getting out of her classroom Min-yeong sees a scary woman from which something is getting out, similar to the birth from Episode 8.
Min-yeong runs down the stairs, but she is in an infinite loop between floors 3 and 2. But she never meets Se-hui which we can see waiting between floors 3 and 2.
Min-yeong trips and sees the 3/2 sign and realises something is wrong.
The monster aproaches and we see the eye division.
Seeing Min-yeong is not coming back, Se-hui goes to look for her. And we can see monster coming down.
The difference from Episode 6 is that now Min-yeong is the one that gets easily scared.
This might be a sign that Dimension changed (in Episode 6).

Episode 3: Special Guest

This episode is about Sae-rom's virtual housewarming.
She is doing a live vlog and wants to trick viewers into thinking that house is haunted by letting a plush toy fall.
Santokki donates 30,000 balloons.
Then the book is moving and falls off the shelf.
Some of the viewers worry for her, while others think it is just a hoax.
She wants to end the live but she leaves it going on by mistake and everyone finds out she faked everything.
While she wants to take the thumbnail for her video, she notices that phone sees more persons in her room.
She then gets smashed by someone looking identical to her.
The way of killing is very similar to the one in Episode 6.
The one killing Sae-rom replaces her.

Episode 2: Destination

In the intro we can hear the news that tell that a shaman was found in a shrine in Gyeonggi. The victim is SHIN, a shaman in her 50s. The shaman must be the shaman from Episode 8.
The news are heard at 2:20.
Now if we go back to Episode 8 and check minute 2:20 we can see something similar to a voodoo doll with a nail sticked in it. And this means death.
Being tired the taxi driver stops.
We see again the clock turning from 3:29 to 3:30.
If we check again the Episode 8 at that minute we see the shaman killing the child.
This is clearly a sign of what is going to happen to the taxi driver.
He wakes from sleep when a woman dressed in white gets in taxi and asks to go to Samjeong Motel in Ilsan. However, GPS show no result for Samjeong Motel.
She asks many times to turn right, but there is road to turn onto.
Next frames show that the taxi has no passanger.
He feels her fingers on his neck, looks back and does not see her, then she appears in front of his car.
He stops, but when he looks again the road is empty. He looks back, she in his car, but her eyes are missing. He gets scared, and she shows him her eyes.
Next frame shows the radio: FM 6.4.24.
Then we can see she took out his eyes, probably to replace her eyes, similarly to how Jin-gyeong replaced her legs in Episode 5.
Another theory about 3:29 is that it is a reference to class 3-2 and hour 9 at which the teacher received the text message in Episode 5. It also the thumbnail of the Episode 2.

Episode 1: Crack

In intro we see Seo-hui PARK, that also appeared in Episode 5. She is anxious and is biting her nails.
On the desk in front of her is a white flower.
She asks the teacher for permission to go to bathroom.
On the walls we see is no. 2 in her school, while Ji-ye KIM is no. 1. We can see that Ji-ye's moving in her photo. This is a hint something is wrong with Ji-ye. The pictures also appeared in Episode 5, since it is the same classroom, but there the pictures are just normal ones, because back then nothing wrong happened to Ji-ye and Seo-hui, being also shown alive and well.
On her way to bathroom Seo-hui notice the lights turning on and off repeatedly.
After she gets in bathroom, we can see in background a presence disappearing on doors.
In the bathroom she heard strange noises and when she looks she sees hair getting in toilet. Then she is pulled by dead Ji-ye only her legs being left in bathroom.