Wilhelmina "Mina" Harker (ne Murray) was a young school mistress (teaching etiquette and decorum) who was engaged to Jonathan Harker, and friends with Lucy Westenra. She visits Lucy in Whitby on July 24 of that year when schools would have closed for the summer.
After her fiancé Jonathan escapes from Dracula's castle, Mina travels to Budapest and joins him there. Mina cares for him during his recovery from his traumatic encounter and the two return to England as husband and wife. Back home, they learn that Lucy had died from a mysterious illness stemming from a wild animal's attack — the animal, they learn, was none other than Dracula taking a different shape.
Mina and Jonathan join the coalition around Abraham Van Helsing, who now turn their attentions to destroying the Count. After Dracula learns of this plot against him, he takes revenge by visiting — and biting — Mina at least three times. Dracula also feeds Mina his blood, destining her to become a vampire at her death. The rest of the novel deals with the group's efforts to spare her this fate by killing Dracula. Mina slowly succumbs to the blood of the vampire that flows through her veins, switching back and forth from a state of consciousness to a state of semi-trance during which she is telepathically connected with Dracula. Mina then uses her inherent telepathic abilities to track Dracula's movements.
Dracula flees back to his castle in Transylvania, followed by Van Helsing's gang, who kill him just before sundown. As a result, Dracula's spell is lifted and Mina freed from the curse.
Mina names their first born son Quincey Harker, after Quincey Morris, who was killed by Dracula's Szgany minions during the final confrontation.