"Hellsing: The Dawn" is a prequel to the main "Hellsing" series, set during World War II. The narrative centers on the Hellsing Organization's efforts to combat supernatural threats amidst the chaos of war. The story primarily follows a younger Alucard, the powerful vampire and Hellsing's most formidable weapon, and Walter C. Dornez, a skilled operative and future butler of the Hellsing family. Together, they are dispatched to investigate and neutralize a Nazi occult project known as "Millennium," which seeks to create an army of artificial vampires to turn the tide of the war in Germany's favor.

The plot unfolds as Alucard and Walter infiltrate a secret Nazi base in Warsaw, Poland, where they encounter the early stages of Millennium's experiments. The duo faces off against vampire soldiers and other grotesque creations, showcasing their combat prowess and the dark, brutal nature of their mission. The narrative highlights the growing tension and rivalry between Alucard and Walter, as well as their contrasting approaches to dealing with the enemy. Alucard's overwhelming power and sadistic tendencies are juxtaposed with Walter's precision and strategic thinking, setting the stage for their complex dynamic in the main series.

The manga delves into the origins of Millennium, introducing key figures such as the Major, who would later become the primary antagonist in "Hellsing." The prequel also explores the ideological motivations behind the Nazi experiments, emphasizing their obsession with immortality and supernatural supremacy. The story is marked by intense action sequences, gothic horror elements, and a grim atmosphere that aligns with the tone of the main series. While "Hellsing: The Dawn" remains unfinished, it provides crucial backstory and context for the events and relationships that define the "Hellsing" universe.