context: Professor Paul Kristan [Ralph Morgan] doesn't know that his mother was bitten by a vampire bat just before he was born. The doctor who delivered the baby some 40 years ago in a bat-infested cave within earshot of angry native drums in the darkest reaches of Africa, handed the bundle of joy to his colleague, Doctor Anders Bizet [Pedro de Cordoba], who raised the boy as his own son. Paul is now a grown man, beloved by everyone in the village because of his "goodness", and engaged to be married to the flower of the village, the beautiful Marguerite Mane [Maxine Doyle].Then the murders start. Three victims have been found lying in the caves, their throats torn open and the blood drained from their bodies. The cry goes up that this the work of a huge and loathsome vampire bat that kills during the dark of night and then carries the bodies into the caves. Only young David [Russell Gleason] cannot accept that there is a bat large enough to carry a human body. The good Professor isn't certain that it's a bat, but he is sure of one thing...the creature strikes only in the dark. Therefore, he suggests that everyone stay home after dusk and keep their lights burning.After bringing some roses to the good Professor, Marguerite meets David in the garden. David has been her friend since childhood, and he's in love with her. However, Marguerite is intent on marrying Professor Kristan because...well...he's so good. David attempts to convince Marquerite that what she feels is respect, admiration, and reverence but not love. Marquerite won't hear of it. She is honored that Professor Kristan (she's trying to learn to call him "Paul") has chosen her, and she intends to make the good Professor a good wife.That night, after seeing his last patient, Paul retires to his study to read his books by candlelight. The night gets darker, Paul falls asleep, and the candle burns out. When he awakens, it is dark outside. Suddenly, his face twists in pain. The good Professor has become the vampire. He climbs through the window of a sleeping girl (Katrina) and attacks her. Somewhat later, his faithful servant, the hunchbacked Zan [Mischa Auer], carries Katrina's body into the caves. When the villagers learn that Katrina has disappeared, they run to the good Professor for guidance. He advises them to go quickly to the caves, but it is too late. Katrina is dead.Meanwhile, back at the good Professor's house, his housekeeper Mother Molly [Lucy Beaumont] has received a surprise visitor...Paul's foster father, Dr Bizet. Bizet is surprised at all the candles that Mother Molly has lit. She explains about the killer vampire bat who only attacks during the dark. Bizet looks concerned. At that moment, Paul and Zan return home. Mother Molly leaves the room to prepare a room for Bizet, and Paul takes the moment to tell Bizet about a problem he has been lately having with headaches followed by "vagueness and exhaustion." Again, Bizet looks concerned but says nothing.That afternoon, Paul introduces Bizet to Marguerite. Marguerite takes Bizet on a tour of her garden, and Bizet uses their time alone to question her about her feelings for Paul. Later, Bizet relays to Paul his belief that, although Marguerite loves him...nay, worships him...she is not IN LOVE with him. Bizet suggests that Paul talk to her to confirm his suspicions. A bit later, Paul decides to walk over to Marguerite's house and talk with her. He takes a lantern to protect him from the vampire bat. Along the way, however, he trips, and the light goes out. Now in the dark, Paul transforms into the vampire. When Bizet finds that Paul is headed to Marguerite's house, he goes after him.Along the way to Marguerite's house, Bizet runs into Paul being carried by Zan. Zan admits that he was afraid for his master and followed him. Paul remembers only that his lamp went out. The three of them continue on to the Mane house and find that the vampire has murdered Marguerite's maid. One of the servants exclaims that he saw a figure...a man...running from the house. "Then David was right," Paul sighs. "The monster is a man." After a town meeting in which the good Professor again warns everyone to go home and keep their lights burning, he also warns John Mane [Carl Stockdale], Marguerite's father, to keep watch over his daughter and never allow her to be alone with anyone. "With anyone at all," Bizet stresses.Who could be committing these heinous crimes? Suspicion falls on Zan, and the villagers unite to look for him. Paul is concerned because each time someone was murdered, he had fallen into a swoon and couldn't remember his whereabouts. Considering this strange malady that seems to have befallen him, Paul decides that it would be best to call off his marriage to Marguerite...so he takes a lantern and heads back to her house. Zan begins to follow, but Bizet holds him back and wrests the truth...it is the good Professor who is the monster, and it is Zan who has been carrying and disposing the bodies in the caves.Meanwhile, David has been visiting Marguerite, again trying to convince her that she loves him, not the good Professor. Confused in her feelings, Marguerite asks David to leave, just as her father returns home. When Paul arrives a few minutes later, John admits him to the house and leaves him alone with Marguerite so that they can talk. Paul begins to explain to her about his strange malady. When he covers his eyes with his hand, Marguerite assumes it is because of the light, so she blows out the candle. Paul panics for a moment, but nothing happens, so he explains that he cannot marry her until he is cured. When he covers his eyes again with his hand, Marguerite turns off the lamp, leaving only one candle burning. Again, nothing happens.Paul decides to come totally clean with Marguerite. He confesses that he may be the fiend who is killing the villagers. Marguerite refuses to buy it. In order to prove that he's not the monster, she blows out the one remaining candle. Suddenly a cloud passes in front of the moon, plunging them into total darkness. "A light!" Paul screams but the transformation has begun. He lunges at Marguerite, who screams. David, who is still hanging around outside, breaks into the house, followed by Zan, Bizet, and the villagers. Zan runs, and the villagers take off after him.Paul lies in a swoon on the floor, and Marguerite has fainted. When she comes to, she tells how the monster went for her throat, after which Zan came through the window, proving that it couldn't have been Zan. Unfortunately, she can't remember the fiend. David chases after Zan to save him, while Bizet waits for Paul to come out of his swoon. When he does, Bizet finally tells him the truth about his mother and the vampire bat whose bite has condemned him to live with the mark of the vampire. In time, he explains, Paul will eventually become fully a vampire. When Bizet tells Paul how Zan has led away the villagers in order to buy some time for his master, Paul realizes that Zan is in danger, and he and Bizet go after him.Zan has gone to the caves. Just as the villagers corner him and are trying to decide whether to hang him, burn him, or seal him in the caves to rot, David catches up and informs the villagers that Zan is not the fiend. Paul and Bizet arrive a few minutes later, and Paul confesses that it is he who is the fiend. After making David promise to love and cherish Marguerite, the good Professor jumps off a cliff. Zan follows suit. The villagers gasp and take off their hats. David holds Marguerite in his arms. [Original synopsis by bj_kuehl].
question: who plays kristan's fiance?
answer: Maxine Doyle