Aboard Voyager, all seems well. The crew has brought their new astrometrics laboratory online, which has allowed them to chart a new course home and shave five years off their journey. Torres remarks that, according to their new star charts, they are about to enter densely populated region of space. Seven of Nine, whose Borg knowledge of the Delta quadrant can now be called upon, explains that the prominent species here is known as they Zaal. They are militarily powerful but peaceful traders who can be expected to grant them safe passage.
Janeway proceeds to make contact with the Zaal, whose emissaries behave just as Seven indicated. One of them comes aboard Voyager and is talking amicably with the senior staff when the ship begins to receive weapons fire. The offending ship identifies itself as belonging to the Krenim Imperium and declares that Voyager has violated its borders. When the security officer reports that the Krenim ship has not, in fact, caused Voyager any damage, Janeway politely declines to leave.
At this juncture, Voyager is hit by a wave of energy. The Zaal ambassador shimmers and fades, as do the Zaal ships, and, as the wave passes through the tiny Krenim fighter, it is transformed into a massive warship.
Aboard Voyager, red alert signals now blare and the bridge is visibly damaged. The Krenim captain now demands that Voyager stand down and prepare to be boarded. The captain declines, and a firefight ensues, in which Voyager sustains even more damage. No one appears to remember that the Zaal ambassador or his ships ever existed.
The unfolding events take place during during the subsequent months, in which Voyager is under near-constant attack from the Krenim, the ship and her crew slowly deteriorating as damage accumulates and resources deplete to dangerously low levels.
The alien ship seen at the beginning, it turns out, is a unique Krenim ship captained by a man named Annorax. His ship's weapon is capable of erasing things from history, up to and including entire species.
In many ways, the show is a fairly typically plotted Star Trek episode. Many of its most memorable moments rely on spectacle rather than theme or character, such as a portion of the bridge being ripped away in a space battle and Janeway gazing out into space through a mere forcefield-protected hole in the bridge's wall. Other elements that passed over me as a child but grate on me as an adult are the inclusion of ham-handed dialogue and sentimental scenes that resonate more on the bathetic level than anything remotely genuine.
However, this two-part episode, which was one of my favorites as an adolescent, is not completely without merit. On the surface level, we have essentially two congruent stories: Voyager struggles to survive the onslaught of Krenim, and Annorax pursues the full restoration of the Krenim Impirium (the one that he remembers) through the erasure of species. It takes two full episodes for the two story lines to fully weave together, and it is Annorax's story that contains the true thematic core.
In order not to be affected by the weapon's timeline changes themselves, Annorax, his crew, and his ship have transitioned out of normal space-time. In this state, they live forever, never aging. They has been making changes, it turns out, for over two centuries, and no matter how many changes he makes, the colony he called his home never appears as part of the Krenim Imperium again.
His character is a successful mashup of the obsessive Captain Ahab of Moby Dick and the obsessive Dr. Haber of The Lathe of Heaven. It is Lathe which The Year of Hell thematically evokes, showing us the futility of Annorax's search for the "correct" temporal erasure that will restore his home. As the story's ending implies, Annorax's path to happiness is quite simple, although it is a path that the depth of his obsession will not allow him to choose. He must become the kind of person who never invented the temporal erasure weapon in the first place.
Janeway is indirectly responsible for the resolution of his character arc, and her own obsession with protecting her crew and getting them home is juxtaposed with Annorax's. This is another particularly effective element of the story. The numerous nautical references land well, too, amongst them Captain Cray and the HMS Titanic.
On viewing The Year of Hell as an adult, the story contains far too much space fighting and explosions for my liking, and it takes a very long time to get to the thematic heart of the story, which, while good, is dealt out in a rather paltry and melodramatic way. I can still recommend this episode as something pretty good and worth watching, but I would first recommend The Lathe of Heaven for a more thorough exploration of the theme of control one's environment versus harmoniously integrating with it.