"Dink, Josh, and Ruth Rose solve a mystery at the Museum of Science"--

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.

When Ruth Rose and her friends, vacationing in Florida, discover that her grandmother is about to invest in a project to recover sunken treasure, they stumble upon evidence that the entire plan may be a fraud.

Dink, Josh, and Ruth Rose investigate the disappearance of a valuable racehorse that Dink's uncle and his friend, Forest Evans, have just bought and entered in a race at Saratoga.

Dink and his friends investigate why pets, like Mrs. Davis's canary, Mozart, are mysteriously disappearing all over town.

While visiting London, Dink, Josh, and Ruth Rose solve a mystery and meet the Queen.

A large bundle of money turns up missing at the U.S. Treasury building and KC and Marshall think they know who did it; however, they aren't quite sure how it was done.

Bradley, Brian, Nate, and Lucy follow clues to find whoever left a rabbit in their first-grade classroom on Valentine's Day, because they are worried the rabbit will get sick and die of loneliness.

Reports of zombies and grave-robbers alarm the people of a Louisiana swampland village, but Ruth Rose, Josh, and Dink begin to suspect that the supernatural may not be the cause of the eerie occurrences.

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.