Rosie and Ella are moving into a new house with dad. It is a strange house, very tall and with lots of windows at the front, but as they explore, they discover there is no garden. Dad says there is, but it is on the roof. The girls are unimpressed, but dad says when spring comes they will make a garden there. Rosie finds a 'twig thing' which they put into a milk bottle on the windowsill, and it begins to put out leaves and a white May flower. Most of the story is about their settling in - the strangeness of the house without any furniture, eating funny pick-up meals, acquiring a cat, going to a new school and playgroup. In the spring they plant their May tree in a pot on the roof. Gentle and leisurely.