On a foggy night at the Williams Wax Museum, Mike Axford is shown the latest addition to the Chamber of Evil, the Green Hornet and Kato. Mike compliments the wax figure maker, Peter Willman, on his ability to capture the likeness, even though he has never met them. Mr. Willman says it is thanks to Mike's descriptions in the Daily Sentinel. Seconds later, Mr. Willman's partner James Rancourt, arrives leading a group of reporters through the Chamber of Evil and describing the crimes of each man represented. The last man is the mysterious Scarf, a ruthless serial killer who killed his victims by choking them with a white scarf. The police were never able to catch him and he mysteriously disappeared twenty years ago.
After showing the reporters the new figures of the Green Hornet and Kato, Mr. Rancourt tells Mr. Willman that he is going to the library to work on how to present the newest exhibit. Mr. Willman tells him that he will probably still be in his workshop, which is in need of some tidying up. Minutes later, as Mr. Willman goes about his work, he is choked from behind by an unknown assailant, who leaves him for dead. As the mystery man leaves, Mr. Willman is able to pull the phone off his desk. Meanwhile, the mystery man makes his way through the Chamber of Evil, passing the area of the stage where the Scarf figure usually stands, but no longer does.
Outside, on the fog-shrouded streets, the Scarf claims another victim, as he strangles a man sleeping on a bench. Moments later, he attempts to attack a young woman, who sees him in time, screams and runs away. Later, at the Daily Sentinel, the young woman describes her attacker to Britt Reid and Mike Axford, noting how strangely he walked and that his face was shiny. Mike asks if the shine was like wax, to which the young woman replies yes. After the young woman leaves, Mike tells Britt that he believes the Scarf is back, but Britt doesn't believe that. Before they can continue, Casey tells Mike that the police have spotted a bearded man near a dead man.
Meanwhile, the police patrol the streets, searching for the killer. A patrol sees him just as he begins to choke a man who was dozing at the bus stop. Interrupted, the Scarf attempts to flee, but the police manage to wound him.
Later, at Britt Reid's house, D.A. Scanlon stops by to find out if there is anything new on the case. Casey calls and tells Britt about the police wounding the Scarf, but losing him in the fog. Casey also tells Britt that Mr. Rancourt called to find out about Mr. Willman. Before hanging up, Britt tells Casey to continue on the research into the Scarf and to bring over anything she finds out. Britt and Scanlon are stuck for an answer, but Kato reminds them that Mr. Willman was the first victim and might know something. Britt calls Casey back at the Sentinel and asks about Willman's condition. She tells him that he is still critical. Kato suggests that there might be some clues at the wax museum.
Later, the Green Hornet and Kato break into the wax museum. Green Hornet examines the wax figure of the Scarf, now back in its proper place, and discovers that the clothes are damp, and that there is a bullet hole in the left shoulder of its jacket and a corresponding blood stain on the scarf it wears. Continuing their search in Mr. Willman's workshop, the duo comes across a locked trunk. After opening it with the Hornet's Sting, Green Hornet finds a manuscript about the Scarf by James Rancourt. Through, Britt discovers that the Scarf spent time with a burlesque dancer that he has tracked down through her real name, Hazel Schmidt. As the Green Hornet, he questions Hazel about her relationship with the Scarf. She says he always treated her like a queen and she never believed that he was responsible for the robberies and murders. She also tells Green Hornet that the last time she saw him, he said he was going away for a while, to become immortal so people would never forget him.
Later still, Britt meets with James Rancourt and asks him to write an article about the Scarf for the Sentinel. After agreeing to it, Rancourt returns to the museum and goes to the trunk, only to find it has been opened and his manuscript is missing. As he leaves, he notices Hazel sitting at a table beside the Scarf figure. She laments that his claim of becoming immortal was false, but Rancourt says it wasn't if she remembered him. Ranting a speech about immortality, Rancourt calls Hazel by her burlesque stage name. She realizes Rancourt is the Scarf and is about to become his last victim when Green Hornet and Kato leap from where they had been posing as their own wax figures and stop. As Kato knocks Rancourt out with a sleeper hold, he sobs that only the Scarf is immortal.
The next day, in D.A. Scanlon's office, Scanlon questions Rancourt. Before he is led away, Rancourt asks if a woman was anywhere near him. Scanlon says no and Rancourt forlornly says it was all a dream. In the secret viewing room, Mike Axford tells Britt Reid about how Rancourt said the wax figures of Green Hornet and Kato attacked him. Britt says that might have also been a dream, but Mike tells him that the police found the figures seated in chairs in the workshop.