"Captain America Annual #9" was the ninth annual issue of "Captain America", and was published in the summer of 1990. Unlike other Marvel Comics, Captain America did not have regular annuals, and this was the first annual in four years. It was also part of a summer annual crossover storyline entitled "The Terminus Factor" that ran through The Avengers related annuals, although that story only takes up the first third of this book, with the next two stories feauting Captain America and related characters in different contexts.
The first story features Captain America and Iron Man, and starts the science-fiction plot of "The Terminus Factor". Terminus is a big Kaiju type alien that is a human looking guy in a giant iron suit, and he was kind of a B-List cosmic villain for Marvel in the 1980s. In this story, Captain America investigates a volcano somewhere in the Pacific Northwest, and after an eruption that damages his magma diver craft, alien germs get inside of the volcano and then spread into food. During a post-volcano rescue celebratory fish fry, the townspeople, and Iron Man, get infected with an alien virus that makes them go crazy until Captain America realizes that he can lure them into snow and they will return to sanity. The story ends with a brief victory, but the spread of the Terminus virus, which converts itself into larger creatures, as it feeds on power sources.
Did I just try to explain that? Basically, this is a standard science-fiction plot about alien invaders and mind control that is interrupted by Captain America's quick wits and iron resolve.
In the next story, Captain America is attending a speech by Reb Ralston, once a member of Nick Fury's Howling Commandoes, and now a Senator, when an assassin attempts to kill him due to him being "soft on communism". While undergoing emergency surgery, there is a flashback story to where the Commandoes, including Ralston, were assisted by Captain America on a mission in World War II, fighting the Red Skull. During the mission, Ralston loses his nerve but regains it, which ties into the present day as he fights to stay alive. He pulls through.
Notice the change in tone: other than the exaggerated nature of the World War II combat, this is a story that could more or less happen in real life, with an obvious but good point connecting physical and moral courage. Unlike the main story, it was written by a relatively unknown comic book writer, Randall Frenze.
The third story features Nomad, a Marvel hero who at various times was Captain America or a follower of Captain America. Nomad shares some of Captain America's patriotic values, but displays them as being a grim and gritty hero sticking up for the little guy. In this case, in a story written by Fabian Nicieza, early in his career, the "little guy" is a murdered prostitute named Patty Joplin. When Nomad stakes out the funeral, he finds her pimp in attendance---next to her old money family. Nomad unravels the mystery, and discovers that while still a teenager, Patty had a baby with her pimp, and that her father could never rescue her from her pimp because he was being blackmailed about his business irregularities.
One thing that was very clear to me was that the stories shifted focus from a "comic book story" with obvious science-fiction elements, to a noir detective drama. The story in the middle was, appropriately, in the middle, being a war story that, despite its exaggerated action, was still "realistic". I don't know if showing different levels and scopes of Marvel's story telling was done on purpose, or just grew naturally from the way the character of Captain America was presented.
This is also related to a fact I mentioned earlier: Captain America didn't have annuals in the 1980s because despite being one of Marvel's flagship characters, he never quite found his niche in the 1980s. As a "street level" character, he was on a par with Spider-Man or Daredevil, telling personal stories that often explored patriotic themes with an emphasis on social justice. But he was also a member of the Avengers, so he was often flying off to fight galactic battles. And because of his position as a leader and symbol, he didn't have the sense of doubt that Spider-Man or Daredevil had. He was a somewhat static character, without much room for character development. And this annual showed Marvel's uncertainty of what to do with the character: was he a steel-jawed soldier to be put in predictable science-fiction stories, or was he (and his supporting cast) a champion of the underdog, dealing with street crime?