Lisa is upset when she realizes that her own father doesn't even know her very well. It's even more evident when he fails to get her the birthday present she wanted. In an effort to get closer to her, Homer hires a detective to spy on Lisa and find out her likes/dislikes.
Lisa is impressed with Homer's new detailed knowledge of her, but when Homer refuses to pay the detective's bill, the guy tries to frame Lisa for a crime.
When the police arrive at the house, Lisa and Homer have to go on the run together, and Homer confesses to spying on his daughter. Lisa forgives him because she knows he did it out of love.
The police trace Homer and Lisa to a circus where Lisa uncovers clues to exonerate her.