Fantastagirl, a second-grade superhero who uses words to save the day, comes face to face with her worst nightmare: the Math Monster! When confronted with problems too big for words alone to solve, Fantastagirl must accept help from her friendly, furry, fraction-loving foe. While Fantastagirl and Math Monster use words and numbers to help her friends and scientist moms, something far more sinister than Math brews on the horizon.