Get Smart Episode #38, Season Two #8.
When Colonel Roger Forsythe is murdered by an "exploding" birthday cake at the hotel Towarna Conrad on the island of Towarna everyone on the island becomes a suspect, but none of them did it.
- Despite repeated references to an "exploding" birthday cake, the cake does not actually explode. Instead, it has a model cannon mounted on it which fires at the victim when he blows out the candles.
- The title refers to the term "whodunit", a sub-genre of detective fiction.