Griffin's Castle by Jenny Nimmo

By Jenny Nimmo.

Dinah is a very smart girl. She and her mother move from place to place--mostly because they don't have much money. Dinah's mother has found love--and Gomer, her mother's boyfriend, has put them in a house that is crumbling and falling apart. Dianh finds it an extraordinary place. She starts at a new school, makes a few friends and finds a couple of mysteries to solve--like where did the lion and the bear living in her garden come from?