Margaret was a former member of the Order and their main alchemist and neophyte. During the plague, Margaret created a potion to aid the Order in curing the people from the illness. Though the people's health were restored at first, the Order soon discovered that the potion had a side effect in transforming the drinker into a vampire, the monstrous creature of the night, and quickly banned the use and stopped Margaret's research. Angry that her work was rejected and halted, Margaret turned heel and used the potion to transform herself into a vampire, escaped from the Order, and began to collect the other vampires as her underlings.
Realizing Margaret's threat to the world, the Order, led by a skilled couple Milos and Ivanna, as well as the two's daughter Petra, transformed into the Order of Vampire Hunting and began hunting down the vampires. Around this time, Margaret came across a young man named Alexander, one of the members of the Order, who was in love with a girl named Valerie, but Valerie instead loved a kind-hearted man named Travis, the game's protagonist, and rejected Alexander's advance, partly because she noticed a deep darkness inside him. Hearing this, Margaret proposed Alexander to become the master of the vampires and that he would be able to get everything he desired, including Valerie's heart, which Alexander accepted, becoming a powerful vampire and increasing the vampires' strength and number further under the help and supervision of the villainess. With Alexander leading the vampires, the Order was dealt a heavy blow, with Ivanna being poisoned into one of them, forcing Milos to seal his beloved wife inside the headquarter's underground as he and Petra continued the battle against their archenemies.
As the vampires started to reach the peak of their power, Margaret began to set in motion of plan to help Alexander in making Valerie becoming his. Taking an advantage of the plague spreading in the town that Valerie and Travis lived, one of their underling sold Margaret's potion to Travis, knowing that Travis would give it to the sick Valerie and thus transforming her into one of them so that once Alexander wed her and made her the Queen of Night, the vampires will become unstoppable. However, Valerie, not wanting to live without her beloved, asked Travis to drink half of the potion, so they both could have a chance at being together. Though this shifted their plan a bit, Margaret and Alexander followed their original plan and had Germaine, the vampire blacksmith and Alexander's aid, kidnapping Valerie and murdering Travis before he got in their way, which failed, and resulted in Valerie and Travis being taken by Petra to the Order after she had fought and killed Germain, as well as Travis gaining the Dragon Bracelet and improving his vampiric ability through the collected crystal tear. Having determined that both Valerie and Travis were no harm to the human society, with Travis even joining their side after helping exorcising Ivanna and allowing her to ascend to afterlife, the Order prepared to release the couples. Seeing his chance, Alexander broke into the Order and kidnapped Valerie, with Travis quickly followed Alexander behind to his castle.
On the way to Alexander's castle, Travis stopped by at an old healer house to avoid the sunlight, which actually belonged to Margaret. Unaware of Travis's identity, the villainess invited Travis to stay at her place until the nightfall and let him stayed in Alexander's room. Eventually, both parties discovered each others' identity and engaged in a battle. Although Margaret initially had an upper hand with her petrification ability, she ultimately lost the battle and was forced to flee, allowing Travis finally tracked down the location of Alexander's castle and met up with the captive Valerie to prepare for the final battle against the vampire master, though Travis' side had lost Milos due to an ambush. Nevertheless, despite Alexander was able to overpower Travis at first with his superior ability and Margaret's aid, Travis was able to fight back against Alexander and Margaret with the help of Petra's silver sword and Valerie's crystal tear, finally destroying Alexander for good. Despair that her adoptive son had lost the battle, Margaret vowed to avenge Alexander and cursed Travis, Valerie, and Petra before she escaped.
In the bonus game set some time after the main game, Margaret carried out her revenge plan by cursing Petra's pendant necklace that she planned to give to Valerie as wedding gift with a potion that returned the latter back to human, but was also imbued with poison that will kill her if she wasn't given an antidote in time, which the villainess send a letter to Travis telling him to came to Rotfolk village if he wanted to save her, which Travis complied. At the village, the villainess ambushed Travis, injected him with the same potion, and imprisoned him in the basement of her hideout, revealing that she conspired with Emil, the mad doctor who wanted to become immortal, to create the potion in order to remove his and Valerie's vampiric power and kill them so that she could steal his Dragon Bracelet, and complete her revenge for Alexander.
Unfortunately for Margaret, Travis managed to escape his imprisonment and created a cure for the poison, used to cure himself and send the rest to Valerie while also imformed Petra about the hideout's location. After disabling Emil, Travis and Petra engaged in the last battle against Margaret, with the former two emerged victorious after Petra shot Margaret with a syringe containing the villainess' remaining poison, destroying Margaret and causing her remain to crumble to dust. With Margaret's defeat, Travis, Valerie, and Petra used the discovered cure to restore the remaining cursed vampires back to human, ending the villainess' reign of terror and finally bringing peace to the land once more.