Homer realizes he doesn't know enough about Lisa, so he hires a private detective to learn more about her. This helps with the father-daughter relationship, as Homer knows what she would want to do. However, the detective, Dexter Colt, has charged him $1000, and few of the charges relate to his work (namely, a $40 steak, super-unleaded fuel and silver bullets [the idiot thought Lisa was a werewolf]). Homer, of course, refuses to pay the bill, so Colt breaks into the animal testing lab, and as Lisa is against animal testing, and some of Lisa's belongings are there, the police assume it was her who did it. Can Homer expose Colt and exonerate Lisa before she's jailed?
—movieguy3