Plot

Evan's visit to his great aunt Katherine's house turns eventful when he finds a jar marked "Monster Blood". He and his new friend, Andy, decide to try it out, but are horrified to find that it is growing.

A yellow car drives up to a house and Great Aunt Katherine is singing classical music with a conductor wand as her record player plays. The car stops and Evan, his mom and dad come out. Evan asks his mom why his dog Trigger has to stay outside and she says that Great Aunt Katherine is allergic to animals. Great Aunt Katherine opens the door and tells him to tie Trigger up and then he can come and have a sugar cookie. Evan starts to bring his bag upstairs but but Great Aunt Katherine tells him to stay out of the room across the hall. Evan put his stuff in his room. and opens the door across the hall anyway. Great Aunt Katherine finds him in the forbidden room makes him leave the room. She goes over to a mirror and it starts to shake, she tries to hold it shut.

At night, Evan tries to sleep. Great Aunt Katherine comes in and close the door.

The next day, Trigger starts barking. A pretty girl named Andy is riding her bike. She stops, and Evan tells her that the dog Trigger is friendly. Andy pets him. Trigger grabs Andy's magazine. Evan and Andy talk about ow strange Great Aunt Katherine is. Evan and Andy go into Great Aunt Katherine's house and find a jar of Monster Blood. They open the jar and a black cat comes out of the jar. They take the Monster Blood out of the jar, and Evan throws it. It bounces really high. They pour the Monster Blood into two jars. They find Great Aunt Katherine driving up and they hide the Monster Blood, Andy stalls Great Aunt Katherine.

Later, in the day, Evan and Andy play outside with the Monster Blood. Trigger eats some of the Monster Blood. Trigger runs off but, Evan and Andy chase him. The dog lays down as if he is sick. Great Aunt Katherine brings out a plate of sugar cookies, Evan takes a bite of the sugar cookie. He tells her that is very good.

Later, at night, Evan tries to sleep, but the container of Monster Blood underneath Evan's bed is growing out of it's container.

The next day, Andy comes over and she asked Evan where the Monster Blood is. Evan says he hid it under his bed and Andy tells him that she had hers in the closet and when she woke up, the container was full to the brim. Great Aunt Katherine plays some loud classical music and conducts while Evan and Andy sneak inside past her. They open the door and Monster Blood is inside growing. They grab a pail and a scooper and try to scoop up the Monster Blood. The black cat looks on as they continue scooping up the Monster Blood. Great Aunt Katherine sneezes, making the record skip. She asks Evan if the dog is in the house and he says no, she takes out a medicine container but it is empty. She opens the door and tells Evan and Andy she'll be back in a few minutes. Evan and Andy go upstairs and pour the Monster Blood into a tub. They go outside and see the rest of the Monster Blood still growing. They find huge dog prints and Trigger is not on his leash. They carry the container of Monster Blood and they pour it into the bath tub. Evan sits on the edge of the bathtub, but it pulls him in. Andy grabs a broom and pulls Evan out of the bathtub. Evan is covered in Monster Blood but it keeps growing out of the bathtub, they put some rags under the door to stop it from growing. Great Aunt Katherine returns home and the monster blood escapes out the door. The black cat appears and morphs into a woman, Sarabeth. Great Aunt Katherine explains that the cat is actually Sarabeth, a black magic witch. Great Aunt Katherine explains the story of what really happened, that Sarabeth was practicing dark magic and the Monster Blood consumed Sarabeth. Great Aunt Katherine sealed the Monster Blood inside the jar and hoped that nobody would find it. Sarabeth tells the Monster Blood to consume Evan, Andy and Great Aunt Katherine. The whole house starts to shake. A overgrown version of Trigger appears and breaks down the door. The Monster Blood consumes Sarabeth. The Monster Blood disappears and Trigger returns to his normal state.

On an airplane, Evan and his other friends, Julie and Curtis are heading to Atlanta, Georgia. Trigger awakens in his kennel as the Monster Blood starts to grow out of a suitcase. This continues into the next episode.