Marvin is a pretty cool kid. He likes to write stories using statistics he collects. However, Marvin has the unfortunate habit of giving everyone he knows a terrible nickname, including Lucy Tinker, the new girl at school.
Lucy has short blond hair that sticks out in all directions, so Marvin calls her a porcupine. He also calls her a stinker to rhyme with her last name. When Marvin notices that all her fingernails are painted different colors, he tells Lucy that her nails look dumb. For Lucy, that is the last straw. She takes one of her fingernails and scratches Marvin’s arm.
Marvin decides to play a trick on Lucy. While she is in the bathroom, he takes her cigar box out of her desk and puts it in her backpack. He notices that Lucy has stolen another girl’s special clown pencil, and he is very angry. When Lucy comes back from the bathroom, she is carrying another girl’s special comb. Marvin thinks Lucy is a terrible person.
Eventually, after a lot of commotion about missing things, Marvin realizes the clown pencil he saw in Lucy’s box was just from the same circus, and not stolen after all. The comb was lent to Lucy fair and square. Worst of all, the backpack Marvin thought belonged to Lucy was really someone else’s.
Lucy tells the teacher that she isn’t feeling so good, so the teacher has the school counselor come to the room and talk to Lucy. Before she does, though, the teacher tells the class that they have to be extra nice to Lucy, because the grandmother who raised her has just recently died. Marvin feels terrible.
Later that day, Marvin sees Lucy catching frogs by the water. He helps her catch an escaping frog, and then apologizes for being such a jerk. Lucy apologizes for scratching him, and they have a good time catching more frogs together. Marvin learns a valuable lesson about not judging people he doesn’t really know.