"Stranger Things" Season 4 starts filming soon and until then, fans have to wait to find out the identity of the American taken captive by the Russians. One fan theory suggests that Murray Bauman is the prisoner because he led the Russians to Hawkins Lab.

A Reddit user claimed that Murray is to blame for bringing the Russians to Hawkins Lab because of his knowledge of the special children. Fans may remember that he looked into Hawkins Lab in Season 2 when Jonathan and Nancy approached him to bring closure to Barb's disappearance.

Murray suspected something sinister was going on at the lab and through his investigation, he learned about Eleven and her psychic abilities. He helped Hopper bring down the lab after he discovered that the Russians were experimenting on children in an underground facility in Hawkins.

Murray knew a lot about what went down in the lab and his knowledge supposedly made him an asset to the Russians. Fans may remember that he has cameras installed in his home to keep him safe, since he fears he has been targeted by the Soviets.

"Picked up by the Russians when he went back to his home base to gather his things. His claims of Joyce compromising his position could be accurate," the fan wrote on Reddit, adding, "The Russians kidnap him from there and bring him with them to Russia when they flee to interrogate him and see what else he knows about The Upside Down."

This means Murray could be the American taken captive by the Russians in "Stranger Things" Season 4. The fan argued that it would be too obvious if Hopper was the prisoner. Instead, he could be in The Upside Down.

Then again, there are also theories that suggest Dr. Martin Brenner (Matthew Modine) could be the American captive. It would make sense given that he is more knowledgeable about The Upside Down and the Demogorgon. Perhaps he even helped the Russians find a way to open the gate to the dark place.

Modine even hinted about the American's identity in a past interview. He sounded certain that he is reprising Dr. Brenner in "Stranger Things" Season 4 and teased at his return as the American captive and not Murray.

Stranger Things season 2
The cast of the Netflix series "Stranger Things." Kevin Winter / Getty