Bosses of the sex-and-scandal drama, which returned to U.S. TV screens this week (beg11Jun12), kept viewers hooked in 1980 with a season-ending plot in which the backstabbing oil baron was gunned down by a mystery assailant.
Producers were so obsessed with keeping the identity of the gunman a secret until the next season eight months later that they went to extraordinary lengths to hide it even from the stars of the show - but now Gray has revealed she was the first to find out.
The actress, who plays J.R.'s now ex-wife Sue Ellen, was required to film a section of dialogue in which she named her sister Kristin Shepard as the would-be assassin, and even that shoot was shrouded in secrecy.
Gray tells TheDailyBeast.com, ""They took me to a recording booth and I'll never forget this. I kept asking, 'What am I saying?'. I had no idea. There was no script. Nothing was ever written down. They said, 'Here's what you're going to say.' The line was in a voiceover: 'Kristin, it was you who shot J.R.' Nobody saw it so the cameraman couldn't report it. Nobody could be there.""