The series opens in modern-day Great Britain with the introduction of the Hellsing organziation, a government-sponsored group with the mission of eradicating all undead intent on harming the citizenry and Queen. To accomplish this goal, they utilize a trained group of soldiers along with the two residents vampires, Alucard and Seras. The organization is run by Sir Integra Wingates Hellsing, the heir to the Hellsing legacy of undead eradication, and she is assisted by her faithful servant Walter C. Dornez.
Seras Victoria was formerly a police officer whose squad was annihilated by a vampire priest during a mission at the village of Cheddar. Taken hostage by the vampire, she was forced to make a choice to live as an undead or die as a human by the nosferatu Alucard. Choosing life, she was shot through the lung and turned by Alucard, now her sire.
She often regrets her choice, as the need for blood disgusts her, but she takes advantage of the new abilities by joining the Hellsing organization as a new recruit.