As housemaid why she had to tolerate inappropriate behavior?

The Housemaid is written by New York Times and USA Today bestseller author Freida McFadden and consists of 336 pages.

As a housemaid of one of the pleasing house, cleaning the entire Winchesters house comprised in her responsibility. But it was not the single task, taking up house owner daughter from her school, cooking flavor some cuisine, and other house chores of work included. Housemaid of Winchester was living in the small room located on top floor.

As housemaid, she had to tolerate inappropriate behavior of Nina when she intentionally threw litter awaiting to be tidy up, and saying peculiar false words, not true about her daughter. She even perceived Nina's husband was living unhappy life with her, but he of brownish eyes, and was handsome man. But Nina had what she wanted, perfect spouse, and walk-in closet and fancy car. 

One day, when housemaid trying fresh and clean outfit, caught by Nina and being she was being watched from behind the closed door. Nina had underestimated genius of her housemaid but was unaware of fact that her housekeeper was of shrewd idiosyncrasy and could do anything unexpected.