Kill Barbara with Panic (1974)

There is something strange about this motion picture...

Barbara has always been overly indulgent of her little sister, Ruth's every whim. Her past comes back to haunt her when Barbara receives news that her younger sister has killed herself and was witnessed by Ruth's only daughter Karen. Barbara immediately returns to the Philippines to mourn her sister and comfort her unstable niece. Upon Barbara's return, she learns the reason surrounding Ruth's mysterious death.