When the seminal British series The Avengers debuted in 1960 as a straight-forward police procedural, no one would have guessed that, in just a few years, it would evolve into the maddest tea party on television. But even after the show started emphasizing humor and satire, there were still occasional episodes designed the scare the bejeezes out of the audience. The holiday themed episode Too Many Christmas Trees (originally broadcast on Dec. 25, 1965) definitely fell into this category.

Directed by Roy Ward Baker and written by Tony Williamson, Too Many Christmas Trees opens with government agent John Steed (Patrick Macnee) being plagued with headaches and nightmares involving a surrealistic forest populated with bizarre cardboard Christmas trees and sinister Santas. His partner Mrs. Emma Peel (awesomely sexy Diana Rigg, now Dame Rigg) drops by Steed’s flat to offer some Christmas cheer before heading for the countryside to attend a weekend holiday party being thrown by wealthy Dickens fancier Brandon Storey (Mervyn Jonhs).

(The episode abounds in in-jokes. In the 1951 film version of Dickens' A Christmas Carol, Johns played Bob Crachit and Macnee played young Jacob Marley. There is also a reference to Steed’s previous partner Cathy Gale, played by Honor Blackman who left the series to take the female lead in the James Bond film Goldfinger. Emma is looking at some of the Christmas cards Steed has received and reads the inscription on one, “Best wishes for the future – Cathy.” Steed looks at the card and remarks, "Mrs. Gale. And how nice of her to remember me. What can she be doing in Fort Knox?")

Steed has been checking up on his old friend and fellow agent Freddy Marshall who is suspected of selling government secrets to the enemy. When he shows a picture of Freddy to Emma, she recognizes him as the man mentioned that morning in the newspapers who died the night before from a brainstorm. Worried about Steed, Emma invites him to join her at the weekend party.

Two of the guests turn out to be enemy agents plotting against Steed, Martin Trasker (Alex Scott) and Jeremy Wade (Barry Warren). There are also some rather suspicious types who seem to be in on the conspiracy, Janice Crane (Jeanette Sterke), a psychic, and Dr. Felix Teasel (Edwin Richfield). It turns out that the bad guys are using Crane’s psychic abilities to drive Steed insane the same way they killed Freddy.

As part of the festivities, Storey is throwing a costume party in which the guests will be dressed as characters from Dickens’ novels: Emma’s costume is Oliver Twist (Steed: “My, you have filled out.”) and Steed’s is Sydney Carton which disturbs him because in one of his nightmares he was dressed in an identical outfit riding in a tumbrel…

The Avengers: Too Many Christmas Trees is available from Netflix (The Avengers ’65, Volume Four).