The exact plot remains sketchy: The protagonist, the son of a farmer, apparantely still young, but of unspecified age, goes to town alone to sell some cranberries. He wants to surprise his parents with the money he plans to bring back. It is not really clear what time this is; probably some unspecified past.
Some tasks have to be solved by the player: The bridge across the river has been destroyed by a storm, then the greengrocer is missing, then we find him in a church grieving over a dead (?) priest. And with that, the thing is pretty much over already, without ever having challenged the player with any actual puzzles. Yes, the story is this disjointed, too, dropping its initial premise and motivation as if it was nothing, but without replacing it with anything less mundane.
What such short and simple games usually try themselves at atmospheric writing, Last Day of Summer fails to evoke any emotions or imagery. Descriptions are ultra-brief (to the point of only listing strictly necessary items and even omitting essential exits, making the game unplayable anyway), interaction attempts are mostly met with failure messages from the parser (not even in the voice of the narrator) whose abilities seem to have been cut down from the engine's standard on purpose.
Even the thin plotline about the priest and his stories remains not only unclear and sketchy, but also pointless: Why would anyone care? What does any of this have to do with the protagonist (who can't even read properly and thus shouldn't really be interested in written fairytales)? Why is he looking for that greengrocer anyway instead of simply using the guy's abandoned stand to simply sell his goods by himself? Not that the latter would have made a more entertaining game, but at least it would have been more coherent.