Idaville's secret weapon against lawbreakers, ten-year-old Leroy "Encyclopedia" Brown, helps the police force solve ten new cases, the solutions to which are found in the back of the book.
The town's ten-year-old walking encyclopedia again solves ten neighborhood mysteries. The final solutions to the cases are at the back of the book, giving the reader a chance to compare his skill to that of Encyclopedia Brown.
The solutions to ten mysteries solved by Leroy "Encyclopedia" Brown are given in a separate section challenging the reader to match wits with the ten-year-old mastermind of Idaville's war on crime.