PLOT

In late August 1839, Daniel, a young man from London, awakens in the dark halls of the Prussian Brennenburg Castle with little to no memory about himself or his past.^[2] All he can remember is his name, that he lives in Mayfair and that something is hunting him.^[10]^[11] Shortly after awakening, Daniel discovers a note written to himself, from which he learns that he has deliberately erased his own memory, and that he needs to descend into the Inner Sanctum of the castle to kill the Baron, Alexander.

The exploration of the dark depths of the castle is also a journey into his own erased past as he unravels the mysteries of Brennenburg Castle, he also finds himself hunted by a dangerous unearthly presence that manifests itself as a corruption that is slowly covering the castle in fleshy, acidic growths, and bizarre monsters against which his only defense is to flee. These events are linked and pertain to why Daniel came to Brennenburg.

Daniel was once a part of an archaeological expedition to Africa, in an attempt to excavate a tomb called "The Tomb of Tin Hinan". He came across a mystical orb buried within the ruins of the ancient temple, and brought its broken pieces back to England where he successfully assembled them. Daniel started to seek information about the Orb's history from a geologist and a professor. However, he began to be plagued by nightmares, and several people who came across his path, and that of the Orb, died horribly at the hands of the "Shadow" that appears to follow his footsteps. Desperate and despairing, he received a strange letter from a Prussian baron named Alexander, who promised protection if Daniel would sojourn in his castle.

Daniel had no other choice but to flee to Brennenburg. As he arrived at the castle, he was greeted warmly by the baron, Alexander of Brennenburg and his servants, who appeared to be very pleased by Daniel's arrival. But the young man was unaware that the enigmatic deity had silently chased him to Brennenburg. Alexander knew this, and promised Daniel that they would banish the cosmic beast forever. Alexander told Daniel all he knew about the Orb's power. Daniel asked Alexander about the letter he sent in response to Daniel. Alexander simply said that things could be done, but at a price. Alexander showed various parts of the Brennenburg castle to Daniel, including the archives, a refinery, a prison where he kept the "criminals", a bottomless pit called the Chancel, and the Inner Sanctum itself, where they could permanently banish the Shadow.

During their visit in the Inner Sanctum, Alexander began to tamper with the Orb, thus enraging the Guardian, whose fleshy residue appeared in the Sanctum. Alexander quickly covered the Orb and the Shadow disappeared. He told Daniel that they had very little time to banish the Shadow. They must quickly start the Warding Ritual before it would be too late. However, Alexander's promise of salvation was a lie. It was revealed then that he is actually an otherworldly life-form who has spent centuries in Brennenburg, attempting to open a "gate" back to his own world. To do this, he needed a substance called "vitae", which can only be harvested from the blood of agonized humans. He also needed a usable Orb. As such, Daniel was a boon to his efforts: Alexander employed him as his personal torturer, replacing his former servants who became the monsters Daniel flees from, and claiming that the vitae would fuel a ritual to banish the Shadow from Daniel's presence forever. Daniel initially embraced this role, particularly when Alexander told him that the humans he was seizing are vile criminals. In order to produce enough vitae, Alexander and Daniel fed the prisoners they tortured with an Amnesia potion, which made them forget the method of their torture, and ensured that they will be just as terrified the second time around, without becoming accustomed or resigned to the pain (Damascus rose is alluded to as either one of the ingredients of the Amnesia potion, or as a flavoring that Daniel perhaps added to the mixture to disguise its taste). As the experiments continued, however, Daniel's faith in Alexander was shaken, and finally shattered when he murdered a little girl in cold blood following her escape from a prison cell.

Alexander saw that the event had taken a toll on Daniel's mind. Taking the Orb with him, Alexander sealed himself in the Inner Sanctum, leaving Daniel to be brutally maimed by the cosmic guardian. Despondent over how far he has come, and furious at Alexander's trickery, Daniel chooses to drink the Amnesia potion himself so that he can atone for his sins without the burden of crippling emotional trauma, leaving but a note to his new self to murder Alexander. The new Daniel found the note his former-self left, telling him to kill Alexander, but also to escape the approaching Shadow as long as he can. As he started to travel in the castle, he realized that his former-self's warning was right. This beast, the Guardian of The Orbs, follows his footsteps, as do the terrible monsters patrolling in the corridors of Brennenburg. Daniel eventually manages to find the Inner Sanctum buried deep below Castle Brennenburg. He breaches its defences with a newly assembled Orb and the help of Heinrich Cornelius Agrippa, an alchemist that Alexander has kept imprisoned in Brennenburg for centuries with the use of strange alchemy. Agrippa, who once studied Orbs with his student Johann Weyer, explains the purpose of the Shadow: it protects the Orbs, slaying anyone who threatens to abuse their power. He mentions also that Weyer managed to travel to Alexander's world using the power of the Orb, and begs a favor: that Daniel separate Agrippa's head from his body with the help of a tonic that will ensure his head will remain alive, and then take it with him.

There are three possible outcomes to the confrontation with Alexander, depending on Daniel's actions at the Inner Sanctum: he can fail to prevent Alexander from returning to his home world and be killed by the Shadow and trapped in eternal darkness, though Alexander thanks him for his "sacrifice", and tells him that what he has done will not be forgotten and he will be celebrated forever; he can destroy the device creating the Gate, causing the Shadow to kill only Alexander while allowing Daniel to escape with his life, content to be leaving Brennenburg having redeemed himself and knowing that Alexander has paid the price for his sins; or he can follow Agrippa's advice and toss his head through the portal, where the Shadow still kills Daniel along with Alexander, however, Daniel is saved when Agrippa finds Daniel, saying that he deserves so much more, and then calls upon Weyer to help him save Daniel, promising the latter that "it will be all right."