A long-necked monster emerges from the Trap Door and eats the breakfast that Berk has prepared for the Thing Upstairs. Afterwards, a big, angry red monster chases Berk and Berk has a hard time getting rid of it again.

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 more wood, Berk opens the Trap Door and a huge octopus-like creature emerges, creating havoc in the kitchen.

Berk is instructed to take care of the garden. He goes out to feed the plants, especially Thort, his master's favourite vegetable, an animal-like plant with a beak that tries to bite Berk. Some wasp-looking things also attack him.

Berk, Boni and Drutt go down to the swamp outside the castle to do some fishing. Berk has left the Trap Door open and is soon surprised by an enormous pink monster who creeps up behind them.

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 for him to fight.

A many-legged creature comes out of the Trap Door and scuttles off down the corridor. Berk goes in search of it and finds an enormous black spider dropping down in front of him.

Boni is bored, but Berk doesn't have time to talk to him. Then Rogg appears from the trap door and throws Boni from the top of the castle. Berk is then 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.

The Thing Upstairs has a cold, so Berk makes him some of his special medicine. Meanwhile, a green lump comes out of the Trap Door and drinks all the medicine - with rather strange results.

Berk is trying to nail the Trap Door down, but it's no good - a large peculiar looking creepy thing comes popping up and changes Berk, Boni and Drutt into all sorts of different shapes.

Berk goes to sleep, but a giant monstrous hand opens the trapdoor, grabs Boni and takes him down below. Now Berk must venture into the spooky strange area beneath the Trap Door to find his friend.

Boni is pestered by Bubo, who has returned again to cause havoc. Berk goes to the rescue, but ends up in the swamp, menaced by swamp creatures. This time, Berk plans to teach Bubo a lesson.

The Thing Upstairs has tooth ache and Berk is summoned to administer to him. Once he finds which head the bad tooth is in, Berk pulls out what he believes to be the rotten one. Meanwhile, a giant muddy thing goes after Drutt.

While the Thing Upstairs is asleep, a little thing comes out of the Trap Door and zooms about so that Berk cannot catch it. Each time it stops it emits a loud fog horn. To Berk's horror, it goes upstairs and into his master's bedroom.

Berk is tidying up and finds an old radio which starts to a familiar tune. As it plays, Rogg and other assorted creatures come out of the Trap Door to dance about. The Thing Upstairs, however, is not amused.

Berk is told to throw out the rubbish and decides to throw it down the Trap Door. But Rogg appears and eats it all up with relish. He then climbs into the dumb waiter and wonders into Him Upstair's boudoir, which lands Berk in trouble.

A creature comes out of the Trap Door and lays some eggs which hatch into green exploding creatures. Berk concerned with the mess decides to push it all down the Trap Door.

Berk is trying to take some photographs of his friends, when a flying creature comes out of the Trap Door. Berk has seen it before and knows that it gives the Thing Upstairs pimples if it gets near him.

Boni has been complaining of boredom again, but Berk has planned a picnic at the swamp. First though he has to see the Thing Upstairs. Meanwhile, a tentacle pulls Boni down the Trap Door.

Berk is asleep. Three monsters, called the Big Mouths, appear out of the Trap Door. They eat everything in sight and make a complete mess of the place.

Berk makes some medicine for his headache, but after drinking it, he becomes a monster.

Something with a lot of eyes sneaks up on Berk while he is trying to unclog a drain. An Elephant Bug that sucks things into its trunk 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 to feed the Thing Upstairs for 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 comes up from the Trap Door once again and starts a fight one last time.

After Berk bungs up a burst water pipe with a worm, he has to get rid of a giant green flying sponge that came out of the Trap Door.

A blue devil 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 color.

Berk, Boni and Drutt play Hide and Seek while the Thing Upstairs is on holiday, until a horrible yellow thing 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 a seemingly endless plague of creepy crawlies coming out of the trap door. Berk uses a bugpipe to lead the creatures far from the castle.

Berk loses his patience with Drutt and throws him down the Trap Door, but he eventually decides to get him back by fishing him out.

It is Boni's birthday, so Berk makes a cake for him and Rogg also joins the two for the party. Drutt is hiding, for initially unknown reasons.

While Berk is giving the Thing Upstairs a slime bath, Drutt mistakenly pulls up a dragon from the trap door.

Berk throws a large amount of rubbish down the trap door, filling it up to the top, but this summons ghosts that torment him for his years of improper waste disposal.

There is a rotten smell in the castle cellar and Berk investigates. He finds out that something pink and smelly came out from the trap door. Rogg comes up and tells Berk, Boni and Drutt that it is a Lump which proceeds to make much noise.

A creature known as the Splund comes out of the Trap Door and teases Boni and Drutt, while Berk is sewing the Thing Upstairs' pajamas.

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.

A pig worm comes up from the Trap Door and eats Boni, Drutt's babies, the Seal, and Drutt. Only Berk can rescue his friends and save the day.

The red thing returns to cause chaos, and Rogg chases it into the swamps, seemingly losing his life in confronting the creature.