"Mad Scientist Tasha sends her humble assistant Austin on a journey to bring three monsters back to her laboratory - Mummy Tyrone, Werewolf Uniqua, and Vampire Pablo. What Austin doesn't know is that a big surprise birthday party awaits him when he gets back."
Austin introduces himself to the viewer as Lab Assistant Austin and explains that today is his birthday. He shows the viewer Tasha, who is playing with toy beakers and wearing a wig and glasses. Austin tells the viewer that she is his mad scientist boss. Austin asks Tasha if she knows what today is, hoping that she acknowledges his birthday. However, Tasha tells him that today is the day that she will finish her greatest experiment ever. She sings "I Got a Secret" and tells him to go to her laboratory.
Tasha sings a reprise of "I Got a Secret" after the backyard turns into a dark lab filled with tables, beakers, and inventions. The mad scientist tells Austin to go get a beaker from a table at the right. Austin walks off sadly. Tasha tells the viewer that she does remember Austin's birthday and is throwing him a surprise party. Austin walks closer in range. Tasha tells Austin that today he will complete a very important mission: to find three monsters (the mummy king, the werewolf, and the vampire) and hand them an invitation. She tells him to get going and bring all of the monsters back to the laboratory after gathering them together.
After Austin walks away out of the laboratory, Tasha tells the viewer that the monsters are the party guests for the birthday party she is throwing for Austin. Meanwhile, Austin tells himself that today is the worst birthday ever as he walks inside the mummy's pyramid. He does not see anyone inside, so he walks in. He reads some hieroglyphics on the wall and reads that he should not go forward.
He walks forward, even though the hieroglyphics told him not to, and reads more. He reads that he "asked for it", and he should not step on any X's. He then realizes that the tiles on the floor he is standing on are all X's. Boulders fall from the ceiling and try to crush Austin. Austin is quick and escapes all the boulders, entering a chamber in which a large tomb is located. A moaning sound comes from inside the tomb, and it is Mummy Tyrone.
Tyrone explains that he thinks Austin is a monster and exits the tomb. He sings "Scared of You" until he realizes that Austin is not scary. Austin gives Tyrone a note that invites him over to Austin's surprise birthday party. Austin asks what does it say, but Tyrone says that it is a secret. They walk to the werewolf's forest and Tyrone asks if this is the laboratory. Austin answers no and says that it is the werewolf's forest. Tyrone is scared of the werewolf and sings "Scared of You" along with Werewolf Uniqua.
They realize that they each are not scary and walk on to the vampire's castle. Uniqua asks if it is the laboratory, and Austin tells her that it is the vampire's castle. They enter and read a sign that says that they cannot go forward. They do go forward and read another that says that they asked for "it". Uniqua is confused at what they asked for until the stairs fall into a pit. They run and scream up the stairs.
They enter a door and see the vampire on the ceiling. Tyrone and Uniqua sing "Scared of You" along with Vampire Pablo. They realize that they are all not scary and Austin gives Pablo the letter. They dance to the laboratory while singing "Hurry Home". They all enter the laboratory and look around. Tasha silently shows the monsters a secret way inside the party room.
Austin is frightened because he is all alone and enters the party room. The lights turn on and the party starts. All five characters sing "Monster Dance Party" as they show off their dance moves. Suddenly, they hear a loud noise. Both Tyrone and Pablo think that it is coming from a monster, only to find out that it was Tasha's stomach rumbling. Uniqua invites the four over to her house for pumpkin pie. They accept as the laboratory transforms back into the backyard. They sing the end song. Austin ends the episode by exclaiming "Oh, brother!"