Having solved the mystery of the periodic table, Perio adopts a little fish called Mathio who loves math. When Perio and Mathio are separated during an ocean tremor, Mathio finds himself trapped inside a cavern deep within an oceanic trench. To get out, Mathio, in the company of two friends who are also trapped, must solve a math problem dealing with fractions. Will Mathio be as successful as Perio was in Perio's Poster?

The Pluck of Mathio is the twenty-ninth book that has resulted from student work in Kid Scribes, a creative writing and desktop publishing class conducted by Excelsus Foundation at schools and other nonprofits nationwide.