The Girl Next Door - Augusta Huiell Seaman

Marcia Brett has noticed unusual activity at the ramshackle and seemingly abandoned mansion next door: a mysterious, veiled lady is seen coming and going out the front door, a different woman is glimpsed through a shuttered window, and most mysterious of all, a pretty, blond girl is seen briefly looking forlornly out an upper window! Along with her best friend, Janet McNeil, the two girls are determined to learn the secrets of the old house and befriend the young girl, but once they do, the secrets only increase. The girl has no idea why she is at this house or even who the women she is living with are! Has she been kidnapped? Are they relatives? No one seems to know. - Summary by Jennifer Dallman