During a supernatural incident of dealing with a village of ghouls, ordinary policewoman Siros Victoria was attacked and dying. At the critical moment, the vampire killer Alcatel appeared, eradicated the ghouls, and turned Siros into a vampire. Naturally, she also came into contact with the mysterious organization behind Alcatel, the Royal Anglican Knights (Hellsing) that defends British Protestantism and fights against anti-Christian monsters. Under the leadership of the current head Itagora Fonnbrook Weingots Hellsing, they took over a series of dangerous and conspiracy-filled tasks. In this process, events related to ghouls emerged in an endless stream, and behind the death, another mysterious organization was planning a shocking conspiracy. Important figures such as Anglico Maxwell, director of the Iscariot Agency of the 13th Section of the Vatican Secret Service, and Father Andrewson appeared one after another. In order to protect the British mainland and Protestantism, the Ninth Crusade was established, and their opponents were the Millennium Army formed by 1,000 ghouls led by the Nazi remnant major. Dark clouds gather over London, and an unprecedented battle between good and evil begins...