Twelve-year-old Katie is dreading the boring summer ahead until she realizes the mysterious neighbor who hired her to catsit is one of the city's greatest supervillains.

"Nansi has been a track star her whole life. When Tania, the girl who has everything, beats Nansi in a race, Nansi knows it was only Tania's new running shoes that gave her the edge. She is determined to get her own pair before the school track meet -- if only she can find $340. Luckily, she has Granny, who sets up Nansi with a job at her friend's salon. But another hurdle comes when she's needed at work and the track at the same time. Good thing...