Being forest monsters, Hiccup and Sneeze don't know what a beach is. Eventually they learn about the beach and the sea and decide to transform the living room into their very own seaside paradise, much to Bibi’s surprise.

Bibi is going on a winter holiday. Hiccup and Sneeze want to tag along too, even though they don't know what winter is. After learning that it snows and it's freezing in winter, they try to persuade Bibi to go somewhere warmer instead.

Hiccup and Sneeze hear a spooky ‘Oooo’ sound and instantly think that there's a scary monster in the house. They tell Bibi about it, but every time she’s around, the ‘Oooo’ sounds disappears. Is there really a scary monster in the house?

It's been raining all day and Hiccup and Sneeze are stuck indoors with nothing to do. Bibi comes up with a series of games and activities to keep them entertained, but things don't quite work out as planned.

Hiccup, Sneeze and Bibi are packing to go on a picnic. When Bibi puts on sunscreen, they misunderstand that she needs protection because the sun is angry with her. So they make special outfits to protect themselves from the angry sun.

Bibi wants to change her hairstyle. She tries on a wig, intending to get Hiccup and Sneeze’s opinion of how she looks, but they don't recognize her! So she plays a trick on them and puts on different wigs, pretending to be different people.

After learning that Bibi was once a tiny baby, Hiccup and Sneeze become worried that she’ll keep growing and growing until she won't be able to fit into the house anymore! They decide to find ways and means to stop her from growing.

Hiccup has been invited to join the 'Best Dressed Vegetables' competition, but Sneeze wants to participate too. Hiccup gets discouraged when she thinks Sneeze’s costume looks better than hers. However, Bibi encourages her not to give up.

Sneeze wants to play, but Hiccup prefers to read instead. So he ropes Bibi in to help him make a baby monster doll to play with! When Hiccup sees the doll, she wants to play with it too. However, Sneeze is a little reluctant to let her.

Hiccup is sneezing out of the blue and no one knows why. Sneeze and Bibi wonder if, like Sneeze, she’s sneezing because she’s scared, or perhaps she’s just feeling unwell. They try different things to get to the bottom of this mystery.

After listening to Bibi read them 'Jack and the Beanstalk', Sneeze has a bizarre dream where he is Jack, Hiccup is his granny and Bibi is the giant as well as a variety of other familiar fairy tale characters.

Hiccup and Sneeze teach Bibi how to celebrate the Monster Spring Festival, where red is the official festival colour. They sing monster songs, make monster snacks and dance the monster friendship dance.

Unware that Hiccup and Sneeze are planning a surprise party for her, Bibi thinks that they’ve forgotten her birthday, and tells them that she's feeling blue. They misunderstand this, thinking that she wants to have a blue-themed party.

Sneeze is worried sick because he can’t find his favourite rubber duckie, Herbie. Hiccup suggests they retrace his steps from the last time he saw Herbie. Will Sneeze ever find his beloved rubber duckie? Or is Herbie gone for good?

Hiccup and Sneeze notice that Bibi is acting and talking funny. Multi-coloured spots are also slowly appearing all over her body. Eventually, they discover from Ellard that Bibi has Monsteritis! Luckily for her, Ellard knows the cure.

Bibi is moving into her new house, a tree house in the woods. Meanwhile, Hiccup and Sneeze are looking for a place to hide from the approaching thunderstorm and they spot a tree house. This is the story of how they all met.

Hiccup decides she wants to start a One Monster band, but soon realises that she can’t handle playing all the instruments on her own. Will she open up to the idea of having Sneeze and Bibi join in?

Hiccup and Sneeze want to set up an art gallery in Bibi’s living room, but they don’t have any art. They set out to create some, modeling for each other, and roping Bibi in to help them as well.

Bibi is helping Hiccup and Sneeze practice being explorers, so they can be real ones in the future. They sail to a dangerous island and trek through an ancient jungle, in search for a priceless idol – all without taking a step out the door.

Bibi’s place has been transformed into the old west. Hiccup and Sneeze are playing pretend as two cowboys in dire need of some horses. Luckily for them, they meet a horse seller and an old lady who help them on their search.

Bibi wants to win Ellard's Amazeballs Dance Contest to surprise Hiccup and Sneeze with a chance to meet Ellard. Not knowing this, they offer to help Bibi prepare for the contest after seeing that she’s struggling to come up with a routine.

After watching one of Ellard's videos about dress-up parties, Hiccup and Sneeze tell Bibi that they want to have one too. However, they can't agree on whether they should have a pirate themed party or a circus themed party.

After watching one of Ellard's videos about pets, Hiccup and Sneeze want a pet too. Bibi suggests they have a pretend pet first, in order to learn how to be responsible. So they make one out of a cardboard box and call him Nutley.

Bibi encourages Hiccup and Sneeze to exercise, but they're not keen on the idea. Bibi even prepares a workout routine for them, but they trick her into thinking they’re following it by pretending to exercise only when she checks in on them.