Fiona, Marlin, Natasha, and Charlie McCready have been adopted by their unlikely guardian, Al, and finally settled into their new home on Pine Island in British Columbia. Fiona is struggling under the weight of trying to keep everything together, not to mention worrying about expenses, while Marlin tries to adjust to her new high school while facing rejections for her cookbook, Thirty Meals a Twelve-Year-Old Could Make and Did!. Natasha is still keeping to herself but is looking forward to learning how to play the violin when school starts. And Charlie is dreaming of what kind of dog she would like. It's been an adjustment, but they are loving being with each other and having Al next door.

Then they receive a letter from Mrs. Witherspoon who took care of them after their parents died and she is coming to visit for three months--an inordinate amount of time for a houseguest. Accommodating a fifth person in the tiny house is hard enough, but to their horror, Mrs. Weatherspoon arrives with a companion, her childhood friend, Jo.

Jo has opinions about everything--what they should eat, how they should behave--and she doesn't hesitate to express them. And sweet Mrs. Witherspoon seems to have fallen under her spell. When she and Jo announce that they are going to extend their stay even longer, Fiona and Marlin are beside themselves. Fiona hates rocking the boat, but there must be a way to get rid of these grown-up bullies so she and her sisters can have the life they wish to lead.