The Baby-Sitters Club Mystery #14: Stacey and the Mystery At the Mall by Ann M. Martin
The Baby-sitters are all taking a class at SMS where they are assigned jobs at the Washington Mall. How cool - going to "school" at the mall! But soon Stacey learns that some pretty bad things are going on there. Besides the regular shoplifting problems, expensive things are being stolen, too. and then Stacey has a big scare when she's working at Toy Town. Is it safe to shop at Washington Mall anymore? The Baby-sitters aren't sure - but they're going to make sure this mystery is solved!