Ep 4. Chapter Four: The Sauna Test

In the fourth episode of Stranger Things season 3, entitled "Chapter Four: The Sauna Test," tensions continue to rise in Hawkins as a new threat emerges. After discovering that lifeguard Heather has gone missing, the group of friends begins to suspect that something supernatural is at play once again.

Meanwhile, Joyce and Hopper continue their investigation into strange power outages around their town, leading them to a suspiciously high-level Russian laboratory. As Hopper's paranoia grows, Joyce tries to keep him in check and focused on finding out the truth.

Back at the mall, Steve and Dustin enlist newcomer Robin to help them crack the code they found in the Russian bunker. As they work to decipher it, they accidentally stumble upon a shocking revelation that puts them all in danger.

As the group tries to piece together the clues and unravel the mystery, they must also confront their own personal demons and past traumas. The stakes are higher than ever before as they face a dangerous new foe and fight to save not only their town, but the world as they know it.