Mother's Day is coming up, and the Baby-sitters have the same problem they do every year: What do they get their mothers? Kristy, especially, wants to do something nice for her mom. Mrs. Brewer has been acting kind of strange and secretive lately, and Kristy's worried about her. But then Kristy gets another one of her great ideas. Why don't the Baby-sitters treat their moms -- and the mothers of the kids they sit for -- to a day off without any kids around? Together with Stacey, the Baby-sitters plan a gigantic baby-sitting party. It's a Mother's Day surprise that couldn't be beat! . . . until Kristy's mom reveals a very special surprise of her own.