Jill is a wonderful girl. I mean, really, wonderful! She is the most perfect human been in the whole world. She has the highest scores on class, she is the prettier of the campus. She even does charity! But, as we all know, nobody is so perfectly made that doesn't have any secret.
The reason for this incredible perfection is uncover the fact that Jill - who would thought about it? - is a psychopath. That's right. She doesn't feel anything: pity, sadness, happiness, love... This woman just does everything mechanically planed for everybody think she is normal.