Dawn is pleased when her mum marries her friend Mary Anne's dad. She insists they should share her room and be real sisters. But trouble starts right away, not only between the girls, but their parents are having problems too. Dawn's mum is laid-back and untidy; Mary Anne's dad is obsessively neat. Furthermore, Dawn and her mother are vegetarians, and the others aren't. In a somewhat unlikely denouement (this is the Babysitter's Club series), Dawn makes her new stepsister believe there is a ghost haunting her room so Mary Anne will move into the guest room. More believably, the parents sort out household tasks and menus, and things look like working out for the better. As usual with this series, the complications are enormous, but the emotions are real.