Two things to note about this one: most interestingly from a story standpoint, this is the first occasion in which Father Unwin actually has a proper confrontation with an enemy agent. This fellow, a foreign agent called Sakov, is a proper, formidable enemy, who deduces that Unwin is part of some British intelligence service, and not a doddering old priest. Had the show continued, I could imagine this character returning for another case or two. I bet that the large Anderson fan community has come up with a fic or two about that.
The other thing is a very funny little sight gag. Father Unwin miniaturises himself and his car, Gabriel, because a garage door is locked and the only way out is through a regular door. The Century 21 team built a quarter-size Model T and drove it along some country lanes for a couple of minutes, leading to the inevitable guy on a bicycle riding into a hedge. That was, of course, Daniel’s favorite moment of the story.
(Note: I can play them, but I’m not presently able to get screencaps from Region 2 DVDs, so many of these entries will just have a photo of the set to illustrate it. Click the link to purchase it from Amazon UK.)