Homer hires a private investigator to learn more about Lisa, until the P.I. frames dad and daughter for a crime they didn't commit.

!! Tropes:

* ClearMyName: Homer and Lisa have to clear their names when a detective steals animals from a lab and frames them.
* MegaMealChallenge: The P.I.'s bill includes 40 dollars for a steak. The detective explains that it'd be free if he managed to eat it all.