The story's protagonist is an Englishman named Wraxall. He travels to Sweden with the intention of writing a guidebook to the country which is to include some interesting incidents from Swedish history. He hears about a large collection of historical documents which belong to a noble family and receives permission to examine them. Wraxall soon becomes fascinated by one long dead member of that noble family, a man named Count Magnus. Count Magnus was an extremely cruel man who had an interest in the occult. Twice, while passing by Count Magnus' tomb, Wraxall expresses a desire to see the Count for himself. When Wraxall expresses the same desire a third time, he soon comes to regret it.
"Count Magnus" has been adapted for film and radio.
In 1863, Mr. Wraxall, an English writer who has already written a guidebook to Brittany, decides that he wants to write another one about a region of Europe that is unfamiliar to British readers. He selects Sweden and travels there early in the summer. Wraxall wants his book to include accounts of some interesting events in Swedish history. He hears that in a manor house in the southwest of the country there is an important collection of historical papers that belongs to a branch of the De la Gardie family. Wraxall travels to the area and is given permission to examine the papers. Although he is also given permission to stay in the manor house, Wraxall decides that he would prefer to take up residence at the village inn.
On the short walk between the inn and the manor house, Wraxall passes by a church. Next to the church is a mausoleum which was built in the 17th century on the orders of Count Magnus De la Gardie, the first member of the De la Gardie family to move to the area. The door of the church is always left open but the door of the mausoleum is always kept locked. Wraxall looks through the keyhole of the mausoleum. He sees some statues and three copper sarcophagi. He is eager to go inside the mausoleum and see more.
From the documents that he reads, Wraxall finds out that Count Magnus put down a peasants' revolt, had its ringleaders executed and made sure that its other participants were severely punished. Wraxall asks the landlord of the inn if there are any traditional stories about Count Magnus. The landlord says that Count Magnus tortured laborers who arrived late for work and that the houses of people who lived on land that Count Magnus wished to acquire often burned down with their occupants inside them. The landlord adds that Count Magnus went on the Black Pilgrimage and returned with something or someone. Wraxall asks what the Black Pilgrimage is. Instead of answering, the landlord makes an excuse and leaves.
At the manor house, Wraxall discovers some books on alchemy which belonged to Count Magnus. He also finds a short piece of writing in Latin, written by Count Magnus himself, about the Black Pilgrimage. According to the writing, pilgrims who travel to Chorazin and salute the Prince of the Air will be rewarded with long life and the death of their enemies and will receive a faithful servant.
While walking back to the inn, Wraxall is occupied with thoughts of Count Magnus and pays no attention to his surroundings. He is surprised to suddenly find himself by the mausoleum. He says, "Count Magnus, there you are. I should dearly like to see you." Immediately afterwards, Wraxall hears the sound of a metallic object falling to the floor. He assumes that somebody cleaning the church must have dropped something.
Knowing that Wraxall wants to see inside the mausoleum, the landlord of the inn introduces him to the local priest. A visit to the mausoleum is soon arranged. Wanting to know more about the Black Pilgrimage, Wraxall asks the priest about Chorazin. The priest replies that, according to the Bible, Chorazin was cursed. He adds that it is sometimes said that the Antichrist will be born there. The priest begins to say that there are some more tales about Chorazin. When Wraxall asks for more details of those stories, however, the priest claims to have forgotten them and promptly leaves.
Wraxall tells the landlord that he has already found out something about the Black Mass. Therefore, the landlord might as well say all that he knows about the subject and say what Count Magnus brought back with him. After a long pause, the landlord begins to tell the story of an event that happened ninety-two years earlier. Two men, Anders Bjornsen and Hans Thorbjorn, decided that they wanted to go poaching at night on the lands that had once belonged to Count Magnus. They were warned not to do so and told that they were likely to meet with, "persons walking who should not be walking." The two men, however, simply laughed. That night, a scream was heard, followed by a laugh that did not sound human. The next day, Anders Bjornsen was found dead with the flesh sucked off his face. Hans Thorbjorn was still alive but had gone mad and constantly pushed away things that were not there.
The priest takes Wraxall to see the mausoleum. The mausoleum's key hangs on a wall in the church near the pulpit. Since the door to the church is always left open, Wraxall realizes that he can let himself into the mausoleum any time he likes. Wraxall sees that two of the copper sarcophagi have large metal crucifixes on them. The third, that of Count Magnus, does not. Instead, their is a full length effigy of the Count in the center of the lid. The edges are decorated with four different scenes, a battle, an execution, a hunt and a man fleeing in terror. The man appears to be running away from a figure that is not quite human. The figure is very short, is wearing a cloak with a hood and appears to have a tentacle instead of an arm. Two steel padlocks hold Count Magnus' sarcophagus shut. A third padlock has fallen to the floor.
Wraxall spends the rest of the day at the manor house. Again, while walking back to the inn, he pays no attention to his surroundings. Again, he suddenly finds himself by the mausoleum and again he expresses a wish to see Count Magnus. Wraxall takes the key from the church and lets himself into the mausoleum. He notices that there is only one padlock on Count Magnus' sarcophagus and there are two on the floor.
The following day, Wraxall receives a letter which says that he has to return to England. In the evening, having said goodbye to the members of the De la Gardie family at the manor house, Wraxall decides that he also wants to say goodbye to their ancestor, Count Magnus. Once again, he lets himself into the mausoleum. Standing in front of Count Magnus' sarcophagus, Wraxall again says that he would like to see the Count. At that moment, the last remaining padlock drops off the sarcophagus and the coffin lid begins to open. Wraxall flees in terror.
On the boat back to England, Wraxall counts twenty-eight passengers, including a man in a long black cloak and a broad-brimmed hat and a short figure in a dark robe with a hood. At dinner, however, he only ever sees twenty-six other passengers. He believes that the man in the broad-brimmed hat is not there at dinner and is certain that the short figure is not there.
Having arrived back in England, Wraxall believes that he is being pursued and remains constantly on the move. While traveling in a small horse-drawn carriage, Wraxall sees two figures at a crossroads. One is a tall man in a long black cloak and a broad-brimmed hat. The other is a short figure in a dark robe robe with a hood. The horse breaks into a gallop when it sees them.
Wraxall arrives at the village of Belchamp St Paul in Essex. The following day, he is found dead. An inquest is held into his death, which means that seven people have to examine his corpse. All seven of them faint when they see it and all seven of them refuse to speak about what they saw ever again.
A short British animated film based on "Count Magnus", directed by Richard Mansfield and written and narrated by Silas Hawkins, was released in 2015.
The story was faithfully adapted for radio by Robin Brooks as the fifth episode of The Red Room, a series of nine fifteen-minute radio dramas. The episode stars Ciaran Hinds as the narrator, Charlie Simpson as Wraxall and Alan Cox as the innkeeper. It was first broadcast on BBC Radio 4 in the United Kingdom on December 22, 2000.