It was another day at the Logan High Science Lab, and Kaz and Oliver walked in after a long night at Mighty Med (location). After treating Brain Matter with partial lobotomy, the two friends forgot to do their homework. When the class sat down, the principal announced that they will have a substitute today, Dr. Frank Russell. Kaz and Oliver recognized that name from Mighty Med's superhero files; their substitute teacher was Brain Matter! When Dr. Russell was checking for homework, he recognized Kaz and Oliver and let them off the hook, for treating him. As Dr. Russell started writing notes on the whiteboard, Kaz noticed a blue wart on the back of his hand, with color similar to him when he was a beast. Kaz and Oliver took Dr. Russell out of the hallway to talk some sense into him, and he revealed he was searching for his former flame Colleen Mackenzie. Oliver remembered he used to have a fifth grade teacher by that name, and the two agreed to find her after school. When school ended, the two searched for Ms. Mackenzie through the building. After a couple minutes of peaking in through classrooms, they finally found Ms. Mackenzie's classroom. The boys let Frank go in and talk to her, while they waited outside. Suddenly, the boys heard a loud shriek from inside the classroom. They went in, only to notice that Frank was starting to slowly mutate back into the beast he was. Ms. Mackenzie ran out the classroom, frightened, as Kaz and Oliver tried to calm Frank down. As Frank started to mutate, he started to seem not as smart as he usually is. Kaz remembered that yesterday while they treated Frank with partial lobotomy, they used a serum to numb his brain, and Kaz must have misplaced it with the miscalculated serum that Frank used on himself to give him his powers. The three realized that they had to get back to Mighty Med without Frank's mutation showing. They snuck him out, pretending that Dr. Russell had an accident in the lab. They got into Frank's car and had to pretend that they were adults driving. When they got to the Memorial Hospital, they snuck Frank in and got him on a gurney, and they searched for the serum that transformed him back into a normal human. They left him in the room with Skylar, and when they came back Frank had fully transformed into the mutant beast. Skylar tried to fight him off, but Brain Matter blasted her with an energy wave and sent her flying, and landing on Spotlight. Oliver convinced Spotlight to temporarily blind him with light, Skylar knocked Brain Matter down, and Kaz injected him with the antidote. Frank slowly mutated back into a human, and he noticed the door open, with Colleen Mackenzie walking through. She explained that she recognized the license plate on his car, and she followed him here. Frank and Colleen were finally reunited. They shared a hug, and got into Frank's car, happily listening to some Mozart.