Lewis, a creative inventor, showcases his newest invention to Mr. and Mrs. Harrington. When a slight malfunction occurs, it creates a life-threatening situation for Mr. Harrington.

Beakman explains what allergies and allergens are. He talks about how the immune system causes the allergic reactions through the production of histamines. He uses a clip to show how a sneeze happens physiologically.

Chandler claims that he is allergic to dogs, but he really isn't. He finally admits that he's actually not comfortable with dogs.

Panda and Clifford are having a fun time together when Clifford realizes Panda is using him to get close to his sister, Lucy. While running away from Panda, Clifford accidentally gets peanut butter all over himself, and he experiences a severe allergic reaction, causing his face to swell and his breathing to slow. Panda looks for the allergy pen to save Clifford and experiences a similar allergic reaction. Despite his condition, he manages to save Clifford, who in turn saves him with another allergy pen.

With the help of the white blood cells, the StoryBots find the ability to combat a virus.