In a new interview with Collider, the Duffer brothers explained that Wolfhard actually managed to work out the details of the spin-off in one guess.
They explained: "Finn Wolfhard knows only because he guessed it. It wasn't like 'is it this? Is it this?' He just goes, 'is it that' and then I think the only way he could do that he's a really smart kid, he's a really creative kid and he just knows me and Ross too well.
"He knows what our sensibilities are and what we're interested in."
The news of a spin-off was announced earlier this year, with the announcement that Stranger Things will end after season five.
“There are still many more exciting stories to tell within the world of Stranger Things; new mysteries, new adventures, new unexpected heroes," said the Duffer brothers.
“But first we hope that you stay with us as we finish this tale of a powerful girl named Eleven and her brave friends, of a broken police chief and a ferocious mom, of a small town called Hawkins and an alternate dimension known only as the Upside Down.”
Speaking about the spin-off, the pair later added to Variety: “We do have an idea for a spinoff that we’re super excited about but we haven’t told anyone the idea yet, much less written it.
"We think everyone — including Netflix — will be surprised when they hear the concept, because it’s very, very different.
"But somehow Finn Wolfhard — who is one crazy smart kid — correctly guessed what it was going to be about. But aside from Finn, no one else knows!”
We can't wait to hear more about this.
In other Stranger Things news, Daisy Edgar-Jones has spoken out about fans drawing comparisons between her and Stranger Things star Joseph Quinn.
Edgar-Jones is best known for her role in the 2020 BBC Three series Normal People meanwhile Quinn shot to fame in season four of Stranger Things.
In a recent game of 'Ask Me Anything' with ELLE UK, Edgar-Jones joked she's 'apparently [...] really great in the most recent season of Stranger Things'.
The 24-year-old continued: "Everyone is saying I look like Joe Quinn, who is brilliant in that series. I do see the likeness.
"I think we could play brother or sister. That was quite funny. Everyone is like 'Oh my God, you’re in Stranger Things'."
You can read more on that here.
Featured Image Credit: Alamy