Following the events in The Fury of the Wolf Man, the deceased lycanthrope Waldemar Daninsky is revived to life when two country doctors surgically remove two silver bullets from his heart while performing an autopsy on him.

Some time later, two students, Elvira (named after Naschy's real-life wife of 40 years) and her friend Genevieve, go searching for the tomb of medieval murderess Countess Wandessa Darvula de Nadasdy.

They find a possible gravesite in the vicinity of Waldemar Daninsky's castle, and the handsome count invites the girls to stay for a few days while they investigate the site.

When Waldemar helps them to uncover the grave of Countess Wandessa, Elvira accidentally revives the vampire by bleeding onto her corpse.

La Noche de Walpurgis was the fifth entry in a series of films to feature the werewolf Waldemar Daninsky.