The hour-long flashback show will air on Thursday 22 October, after a regular episode of the soap.
The plans have been likened to the successful Lucy Beale killer reveal in ‘EastEnders’, as the BBC soap’s bosses also used a flashback episode to reveal the truth.
‘Emmerdale’ boss Kate Oates recently explained the storytelling decision, saying: “This won't be the first time 'Emmerdale' has broken its 'house style' of storytelling; but it will be the first time we've told a story in a non-linear way.
"What makes this 'rewind' episode special is that we won't just learn who shot Robert, but two other big secrets that will propel the show into an exciting, emotional and dramatic winter."
There are currently a number of suspects in the frame, and even the ‘Emmerdale’ cast aren’t too sure who’s guilty.
Kelvin Fletcher and Ryan Hawley, who play Andy and Robert, have previously given their predictions.
“I think Aaron’s got the biggest motive, and score to settle,” Kelvin said, while Ryan pointed the finger elsewhere: “Lachlan’s been creeping in the shadows and lurking about. Robert’s wronged so many people.”
See all the latest ‘Emmerdale’ news and spoilers here.