In the years before Kain's birth the Circle of Nine - Guardians of the Pillars - protected Nosgoth. However, an enemy entered into the circle and cruelly murdered Ariel - Balance Guardian - which drove Nupraptor insane. His insanity unleashed a psychic wave poising the minds of the remaining guardians. Soon after, the pillars fell into a state of decay and transformed Nosgoth - once rich and beautiful - into a wasteland.
The son of an aristocrat from Coorhagen, Kain was born into a world of disease. One night a band of assassins murdered and impaled Kain upon a sword and left him to die, until the Necromancer Mortanius resurrected him as a vampire. Transfixed with hunger Kain tracked down and destroyed his assassins.
Kain soon realized that his journey is far from over, as these pitiful men were merely the instruments of his death - not the cause. Instructed to journey to the Pillars, Kain met the specter Ariel. She informed him that the only way to restore Nosgoth and cure the Pillars is to track down and kill each remaining guardian. At first, Kain only sought to restore the Pillars in order to cure himself from his accursed form. However, he soon realized the importance of his quest. It was the noble Circle of Nine that bought the Sarafan and wrought the "Vampire Purges." Filled with anger and disgust for the humans, Kain hunted down each member of the Pillars.
During Kain's odyssey, he encountered Vorador - an ancient vampire. Vorador advised that Kain stay out of human's affairs as it only beings suffering.
Against Vorador's warnings, Kain became intertwined in a bloody battle with Ottmar's Army of Hope against the ruthless Nemesis. Conveniently, Kain stumbled upon a time streaming device and he is flung 50 years into Nosgoth's past.
Hoping the change the course of history, Kain hoped to find and assassinate William the Just - later to become the hated Nemesis. Using the soul reaver, a powerful blade that can consume the souls of its victims, which he found in Avernus Cathedral, he defeated William.
Upon his return, Kain witnessed Vorador being guillotined by Moebius. It appears after the death of William the Just, Moebius led a crusade against the vampires and managed to kill ever vampire except for Kain. Infuriated at that Moebius choreographed his every moves, Kain attacked and beheaded Moebius.
Returning to the pillars, Kain sees Mortanius was the one who ordered Ariel's and his own death. Fueled with anger and vengeance he killed the Necromancer, only to witness that a dark entity has seemed to posses him. After the final confrontation with this darn entity Kain has finished his quest, yet the Pillars are not restored.
Once again, the specter Ariel appeared to him and informed him that he is Ariel's successor as Balance Guardian and in order to restore the Pillars and Nosgoth, he must sacrifice himself for new Guardians to arise.
Disgusted with human treachery Kain chooses to damn Nosgoth for eternity and to rule the world in damnation. This act completed the Pillars destruction and they toppled as he sealed their fate.