One of the creepiest OL episodes ever. Way ahead of its time. Done in the trademark OL film noir style and would be far less effective in color. The idea of aliens planting inimical technology reminds me a bit of the Interocitor in This Island Earth (1955). Not to mention the other OL episode, Keeper of the Purple Twilight.
Today, I wonder what Harold Finch would do if he found his machine surreptitiously viewing and reviewing this episode of the OL. ;)