While this story is very short and rather simplistic, it is pure paranoia fuel. Granted, some of that is dulled by the fact that milkmen are not as prominent as they were back in the day, but the concept is still pretty unnerving.
The protagonist is a milkman named Spike. We're not really told a whole lot about him, but he's not the guy you want delivering your milk.
Why? What could possibly go wrong? Well, Spike has a habit of adding things to the deliveries. Things like spiders, chemicals, and toxic gases. There's no rhyme or reason to what he does. It isn't like he's disgruntled and getting back at people who have mistreated him. He just does it for the sake of it.
Even people who don't put in an order aren't safe as he leaves cartons filled with cyanide gas for one resident when they tried to be passed over.
I can't imagine Spike holding down an official delivery job for very long. I think it's safe to say that he's just a crazy guy who happened to get his hands on a milk truck. Whether he just stole it or whether he was a milkman at one point and kept the truck for himself is up for speculation.
As you can guess from the title, there is a second "milkman" story, which incidentally, is next. Oddly enough, that story was published earlier while this one wasn't. It makes me wonder whether the subtitle was added later. Having a (milkman #2) attached to a story with no #1 to precede it is rather bizarre, but Star Wars started from episode 4, so maybe it was intentional.
I'm interested to see how the second story ties into this one. It could be a bona fide sequel or it could just be a thematic link.
This is a story that's pretty review-proof. There isn't a whole lot of fodder for analysis or discussion, but like I said, it is a pretty terrifying concept and that alone is enough to carry this one.