Karen's Spy Mystery is the 111th book in the Baby-Sitters Little Sister series.
Back Cover SummaryEdit
Nancy's family has hired somebody to take care of their house while they are on a trip. Karen wants to make sure he is doing a good job. So she watches him closely. And she catches him snooping around! Karen is pretty sure he cannot be trusted. But she has to figure out what he is doing before she can turn him in.