Meet Pat and Patty Flaugherty (pronounced "flair-tee"), teenage fraternal twins who have a penchant for getting themselves involved in mysteries. They don't plan to become professional detectives, but never being ones to dismiss a challenge, they attack these mysteries wholeheartedly until they resolve them.

As a team, they each bring their unique strengths to the investigations: Patty's keen eye for observation of details and Pat's ability to "read" people. But with very different personalities, they are often at odds with each other during the process. Pat is headstrong and can be impulsive; Patty is levelheaded and practical although sometimes too critical of her brother.

Pat and Patty Flaugherty are drawn into their second mystery by an old friend who is now in college. When he appears on their doorstep with a "little problem" that he is reluctant to divulge, the twins are quickly caught up in an investigation of a scheme to launder counterfeit money throughout their home state.

The mystery moves to the university campus where Pat and Patty search for missing school supplies and end up finding a campus secret that helps their friend and also leads them to solve a 35-year-old murder case in the Mystery on Campus.