We actually featured one of the insert sets, "The Cage, Uncut", before, in our newsletter of the 6th of September, 2025, as the diary date for Monday the 8th of September, and I have to say that despite that being a special issue, it is a much more normal looking card than this. For here we have a card with cut corners, half diamond cuts to the sides, and even the picture is quartered into images.
The episode on this card, "The Immunity Syndrome", was the eighteenth episode of the second series, and it was first shown on the 19th of January, 1968. It starts out by telling us that the crew are headed for leave when they receive a garbled message. Whilst a better connection is sought, Spock tells them that the Intrepid, a Vulcan starship, has just lost all connection, and presumably been destroyed. He knows this because he too is a Vulcan, and they are able to connect by a form of telepathy. So instead of getting time off the crew investigate, only to find that a nearby star system has also disappeared. The cause is discovered to be a huge energy-sapping amoeba, which also traps the U.S.S. Enterprise, but does allow a shuttle out, with Spock aboard, and he discovers a way to kill it. Unfortunately his message is not delivered entirely, and Captain Kirk has no choice but to destroy the amoeba with an anti-matter bomb. However he also has time, just, to drag Spock`s shuttle out of where it is being captured and he returns safely to the ship.
I have not been able to find out if this episode was featured on any other set of cards. Maybe you know. I did find out that the first set of "Star Trek" trading cards was circulated with Leaf gum in 1967. The images were in black and white and had large black banners at the bottom with the titles in white lettering, but it was not a great success. It is rare today though, as it was only issued in Illinois and Ohio, and there were licensing issues which led to its withdrawal.