A good question!
The basic situation tells us quite a bit about the story.
The basic situation is the setting combined with the characters. The setting is on board a spaceship, but a small one that has limited supplies and a specific mission, and which operates under a specific and strict set of laws. The characters are the pilot (Barton) and the stowaway (Marilyn Cross). These two aspects of the situation set up the story: you could say they are the story.
The pilot is charged with taking medicine to a distant planet to fight a plague. Many lives rest on him getting the medicine there. However there’s only a limited amount of supplies in the ship, and so even though Marilyn meant well—she only wanted to see her brother—he must put her out of the ship (killing her).
As the story says, “EDSs obeyed only physical laws, and no amount of human sympathy for her could alter the second law.”
The situation is the story.