When they discover that one of the thumbs has been broken off the statue in the Lincoln Memorial, KC and Marshall set out to learn what happened and restore the thumb before a ceremony honoring the sculptor.
When KC and Marshall see lights flickering at night in the Washington Monument, their investigation turns up a monkey, a hole in one of the monument stones, and a hundred-year-old mystery.
While visiting Thomas Jefferson's home, Monticello, presidential stepdaughter KC Corcoran and her friend Marshall investigate the theft of a box of toy horses given to Jefferson by his grandchildren.
KC and her friend Marshall accompany KC's stepfather, the United States President, to remote Camp David, where they find clues that point to either ghostly or criminal activity.
KC and Marshall investigate the theft of a precious emerald, brought by representatives of the Chinese government to bring luck to two baby tigers born at the National Zoo.
KC and Marshall take a tour of the Bureau of Engraving and Printing, and when they discover that someone has been stealing bricks of newly printed money, they resolve to find the thief.
"KC and Marshall convince the President of the United States to pardon more than one turkey for Thanksgiving, but all 117 of them are stolen off the National Mall"--
