What is the movie christina's house about?

The teenager Christina, her younger brother Bobby, and their father James Tarling moves to a rented house in a small town in Washington to be close to Christina's mother Joanne, who ... "Christina's House " is low paced, low budget but it is not a bad horror movie. The screenplay plays with very few characters, maybe due to the limitation of the budget, the viewer knows that one of them is the serial killer, but there is no clue along the story indicating who the criminal is. Although quite exaggerated