Step by Step (1991)

Season 3: Episode 21

Cody is writing a 40's style mystery for his creative writing class. He gets an idea when Karen proclaims her diary is missing. His pun-filled story is played out by the Lambert/Foster family. Kitty Meow (Karen), who sings in the famous trio the Andrews step-sisters, lost her diary. The suspects are as follows: the other two Andrew's step-sisters (Dana and Al), the establishment's piano player (Brendan), comic (JT), and other singing act, Miss Honey Dew (Carol). With the help of the lab technician (Mark), Sam Spud (Cody) discovers it was Honey Dew. In real life, Al turns out to be the one who misplaced Karen's diary.