Mary Anne has never been a leader of the Baby-sitters Club. She's left that up to Kristy... or Claudia... or Stacey. But now there's a big fight among the four friends, and Mary Anne doesn't have them to depend on anymore. It's bad enough when she's left alone at the lunch table at school. But when she has to baby-sit a sick child without any help from the club members, Mary Anne knows it's time to take charge. The Baby-sitters Club is going to fall apart unless somebody does something–fast. Maybe it's time for Mary Anne to step in and save the day!