Fina Mendoza, the ten-year-old daughter of a congressman from California, solves mysteries on Capitol Hill. Fina has a new mystery on her hands. Her entire fourth grade is competing with fifth graders in a reading competition to see who can read the most pages. The prize: free pizza. Unfortunately, her class loses the contest. But pizza mysteriously appears anyway at the front door of all the fourth graders. How did that happen?
Meanwhile, Fina’s father and the parents of nearly everybody else in her class is working in the U.S. Capitol on January 6th to certify the election results. News of the insurrection reaches Fina and her classmates in the middle of a geography lesson. Fina’s father, Congressman Arturo Mendoza, arrives home safe and sound and tries to explain why people were angry, comparing it to the anger Fina herself felt when her beloved Dodgers discovered that the Houston Astros were cheating by stealing pitching signs.
In class the next day, students discuss the events of January 6th and also the mysterious pizza delivery. They talk about the role of losing in a democracy, how John Adams was angry that he lost his election, and how he stayed angry for many years with the man who won, Thomas Jefferson.
Fina solves the pizza mystery with the help of her clarinet-playing sister Gabby and the congressional dog she walks named Senator Something. Fina also suggests that 4th graders can be gracious losers by writing letters to the 5th grade, the way Adams and Jefferson did, becoming perhaps not friends, but at least opening a door to reconciliation.