Don't you open that Trap Door! You're a fool if you dare! Stay away from that Trap Door! Cos there's something down there!
Berk is busy preparing his master's breakfast - from worms and other vile concoctions, when a strange yellow creature comes out of the trap door in the kitchen floor and eats the breakfast, closely followed by a large Big Red Thing which chases Berk until Berk hides behind a mirror - the ugly monster gets a nasty shock and retreats down the trap door. Prompted by his master's demands for breakfast, Berk takes the yellow creature, which has eaten everything and fallen asleep, and feeds it to his master as Chef's Special...
Berk is trying to put up some shelves for his master and is using Boni as a prop to hold up the shelf. Looking for some more wood, Berk opens the trap door, but a huge octopus-like creature emerges with writhing arms and creates havoc in the kitchen.
Berk is instructed to go and see to the garden. He goes out to feed the plants, especially Thort, his master's favourite vegetable. Returning to the kitchen he opens the trap door to get some worms for dinner, but a swarm of large bees come out and sting him. Berk runs out to the garden followed by the bees, who are eaten by Thort. When the Thing Upstairs shouts for food, Berk suggests a salad ...
Berk, Boni and Drutt go down to the swamp outside the castle to do some fishing. Boni is moaning because he finds it boring, but Berk has left the trap door open and he is soon surprised by an enormous pink monster who creeps up behind them. Berk is so frightened he falls into the swamp, only to find the monster is friendly and wants to join in...
Berk is cooking again, when something invisible comes out of the trap door and starts throwing things about. Berk scores a direct hit in retaliation with some yellow goo and the little creature - Bubo - becomes visible and bright yellow. When Berk eventually catches the naughty Bubo, he finds a hole in the top of his head, blows him up like a balloon and lets him off into the air and lets him drop back down the trap door.
Something large and black with "lots of legs" comes out of the trap door and scuttles off down the corridor, but Berk won't believe Boni. He goes in search of it and finds a tiny spider, thinking it must be Boni's monster, but just then the enormous black spider drops down in front of him, wraps him in thick green web and chases him into the kitchen. Drutt spins the spider up in his own web and Berk is able to push it back down the trap door.
Boni is bored, but Berk doesn't have time to talk to him. Then Rogg appears from the trap door and takes Boni out 'to play' on top of the castle ramparts. Boni talks and talks and bores Rogg until he falls off the castle on top of Berk, who has come in search of Boni. Boni is left talking to himself...
Berk and Boni are going through things in a room that's been left untouched for a long time. Berk finds an old book of spells and reads one out, summoning up the 'Ghostly Ghoulies' ... They rush back to the kitchen to find the trap door thumping open and shut and ghoulies floating about the place. To make them go away he has to read the spell backwards...
The Thing Upstairs has a cold, so Berk makes him some of his special medicine. Meanwhile, a 'horrible green gobby lump' comes out of the trap door and drinks all the medicine, with strange results. As Berk drags the little green thing back to the trap door, he finds the creature's mum has come out too - a large yellow lump. Berk, Boni and Drutt all end up with colds.
Berk is trying to nail the trap door down, but it's no good - a large peculiar looking Thingy comes popping up and changes Berk, Boni and Drutt into all sorts of different shapes, before eventually disappearing again, leaving them back to normal.
Berk goes to sleep but something horrid emerges from the Trap Door and kidnaps Boni. Berk goes down to rescue him. This is one of two episodes which is revealed to be a dream at the end, the other being "Moany Boni".
Bubo, the spout-headed troublemaker from "Gourmet's Delight" is back and he's pushing a distressed Boni about the workroom on his trolley. He takes Boni out to the swamp and starts beating him with a stick. Berk and Drutt arrive, lured by the sound of Boni's moaning that Berk had mistaken for singing. Bubo pokes Berk in the keister with the stick, sending the former straight into the bog, and Drutt tumbles in as well. They both get back out and Berk throws Bubo into the swamp. The three friends head for home, sure they've seen the last of Bubo, who can be seen swimming for shore.
The Thing Upstairs has toothache so Berk goes to sort it out. Drutt wedges open the trap door so he can eat some worms, inevitably releasing a hungry slug thing which decides to eat him instead. This episode is centered on Drutt trying to escape from the creature.
A noisy little thing has escaped and Berk must catch it before it wakes the Thing Upstairs.
Whilst cleaning out his cupboard Berk finds an old radio and all the monsters (past and future) emerge from the trap door to dance to the theme tune. This episode acts as more of a music video of the series.
Rogg returns and eats all the garbage; he then causes trouble by going up in the lift to the Thing Upstairs's room.
Something horrible escapes and lays its eggs. Little things hatch quickly only to pop almost immediately, causing havoc for poor Berk.
Berk is trying to take a photograph of Boni and Drutt but gets interrupted by a green flying bat thingy.
Berk is taking everyone on a picnic but has to scratch the Thing Upstairs before he leaves. While he's gone something pulls Boni down the trap door. This episode is centered on Boni and his experiences through the trap door caverns then the swamp.
Whilst everyone is asleep four near-identical greedy things emerge and raid the kitchen, causing a mess.
Berk makes some medicine for his headache, but after drinking it he turns into a horrible monster.
Something with a lot of eyes sneaks up on Berk while he's trying to unclog a drain. Another thing that sucks things into its mouth climbs out too, and in the end solves both his problems.
All the rubbish Berk keeps throwing down the trap door comes to life and starts spitting slime at him.
Berk tries to pick mushrooms for the Thing Upstairs's breakfast, until one of them runs off.
Fed up with running around after the Thing Upstairs, and fending off the trap door monsters, Berk leaves.
Bubo (in his final appearance in the programme) comes up from the trap door once again and starts a scunge fight.
After Berk bungs up a burst water pipe with a worm (though the worm works itself free), he has to get rid of a giant green flying sponge that came out of the trap door.
A purple, devil-like horrible thing with supernatural powers comes up from the trap door and starts casting annoying spells on everyone. Boni gets a body (and starts making goat noises), Berk changes orange, then red, then grows large, and Drutt continuously changes colour (green, yellow, and blue).
Berk, Boni and Drutt play Hide and Seek while the Thing Upstairs is on holiday, until a horrible custardy yellow monster comes up through the trap door and interrupts.
One of the Thing Upstairs' eyeballs falls down the trap door and Berk has to go after it.
Berk and Boni have problems with lots of creepy crawlies coming out of the trap door. In a parody of The Pied Piper of Hamelin, Berk uses a bugpipe to lead the creatures far away from the castle.
Berk loses patience with Drutt and throws him down the trap door, but he eventually decides to get him back by fishing him out. Unfortunately, Berk fishes out a red horrible thing that looks cute but, as Boni finds out, is actually anything but.
Berk bakes a birthday cake for Boni but Drutt has a surprise of his own.
While Berk is giving the Thing Upstairs a slime bath, Drutt mistakenly pulls up a dinosaur-like thing from the trap door.
Berk throws rubbish down the trap door, filling it up to the top, but this summons ghosts that Berk thinks are after him.
There is a rotten smell in the castle cellar and Berk investigates, he finds the source of the smell; something pink and smelly came out from the trap door. Rogg comes up and tells Berk, Boni and Drutt that it is a "Lump", and it proceeds to make lots of noise.
The "Splund" of the title comes out of the trap door and teases Boni and Drutt, while Berk is sewing the Thing Upstairs' pyjamas.
It is the middle of winter and Berk has to mend the Thing Upstairs's heater. Rogg comes up from the trap door with a green fuzzy thing stuck to him. This is the last time that the Thing Upstairs is heard, with the following episode being the last time he is actually referred to.
A pink worm-like thing comes up from the trap door and eats Boni, Drutt's babies, the Thing Upstairs' dinner, and Drutt (in that order). Only Berk can rescue his friends and save the day.
The series finale. The red thing from episode one returns to cause chaos, and Rogg chases it into the swamps and confronts it.
