Masters of the Upside Down.
Metallica met up with Stranger Things star Joseph Quinn for a full-on jam session ahead of their highly anticipated performance at Lollapalooza.
As Quinn's character high school misfit, Eddie Munson performs the track in the final episode to defy a demons' psyche-corrupting ability, Metallicas 1986 single Master of Puppets looms large in the final season plot.
Fans have been waiting patiently for Quinn and Metallica to join forces in real life since the episode aired.
The 29-year-old British actor revealed that the song was all he had been listening to for two years prior to filming the hair-raising closing scene in the video shared to various social media accounts.
Backstage at the festival venue, he told the band that he feels very connected to you.
The sentiment evidently went both ways. Im a big supporter of [the program]. I have been since Season 1, led singer James Hetfield, 58, spoke.
It's been a bonding experience for my kids and I, according to him.
In an Instagram post earlier this month, Metallica publicly declared its approval for the shows' incorporation of Master of Puppets.
The Duffer Brothers' approach to Stranger Things has always been above and beyond, so we were heartbroken for them to include Master of Puppets in the program, but also to have a pivotal scene built around it, giving a shout-out to Matt and Ross Duffer.
We were all ecstatic to see the end product, and when we did, we were completely surprised.
The band members presented Quinn with a personalized and signed replica of the B.C. Rich electric guitar Eddie uses on-screen.
Although the 40th anniversary of the songs' release is only a few years away, the fact that it figured prominently into this season of Stranger Things propelled it to the top of the charts internationally in early July.