Each week it featured a short murder-mystery drama enacted in front of a panel of four
celebrity guests who then had to establish who the murderer was. One week there was a smuggling mystery and no murder. The panel members could interview the remaining characters, with the proviso that only the guilty party or parties could lie. Each panellist could also request to see a short replay of one section of the initial drama, which would often include events as they occurred and flashbacks as seen and narrated by individual suspects. For series 1, the entire audience also took part in guessing who was guilty (with the winner winning a prop from the set). For series 2 and 3, four members of the audience formed a panel, but did not question the suspects, with the winner taking away a 'Whodunnit?' trophy (a magnifying glass in a frame). For series 4 and 5, the audience panel was dropped and a
TV Times competition winner formed part of the main panel (taking away a prop from the set if they won the game). For series 6, they were dropped entirely. At the end the compere would reveal the guilty (usually a murderer) with the catchphrase "would the real 'Whodunnit' please stand up?".
Whodunnit? originally adopted a conventional panel-game studio layout, for series 2 some episodes would use the murder scene for the panel part of the show, with this being fully adopted for series 3 onwards. ==Transmissions==