Mystery in Gram's Attic - Shadow Boy Mystery Series, #4

A mysterious lost land deed and a missing map hidden somewhere in Grandma's attic can save Ellen and Troy Baron. The twelve-year-old twins live with their mother in a falling-down house with no hot water or a working toilet, and most nights they all go to bed hungry and dirty. Troy is bullied by the boys in gym and Ellen faces the "snoots" every day, girls who make fun of her. Their father may be hiding from the police and their grandmother who can help them can't get in touch because they don't have a telephone.
Their mother has Cerebral Palsy and walks with a jerky limp, but everyone thinks she is drunk. Ellen and Troy are afraid something will happen to her and they will be alone with no-one to help them. Huby returns to Arizona in book four of The Shadow Boy Mysteries in his hardest quest yet, to save the twins and their family before it's too late.