This mission could have been just a routine inspection, but things went sour when a certain agent Amon decided to "call the bluff."
It began with a disappearance, as usual. The missing subject, SCP-014, a man who turned into concrete, was kept at an abandoned insane asylum. The agents went to investigate but found more than they had bargained for. Among the hundreds of spirits that inhabited the asylum was a witch that had been contained by the agency long ago and placed under lock down at the top floor of the building. Two SCP guards on station told the agents to stay away from that floor but, of course, they couldn't resist.
After some scary ghost sightings and knocking out agent Amon in a hallway and leaving him there, the agents discovered a sealed metal door with symbols around it. Agent Amon woke up in what can only be described as the "spirit realm" where he went to the same door to find grasping hands reaching out from the shadows. This was when he "called the bluff" and reached in. Consequently he was pulled in and the witch in containment was able to posses his unconscious body while trapping him in her contained, decrepit one.
The witch then convinced the other agents she was, in fact, agent Amon and before they realized that wasn't so, escaped to the city of Spokane. This was after angering the hundreds of asylum spirits and killing agent (father) Johnson, the occult specialist of the group.
The agents were able to break into the previously contained witch's room and take the aged body holding agent Amon's spirit with them on their journey to Spokane.
The witch escaped to an apartment building previously visited by agent Amon on a personal mission where he confronted an entity known only as "The Hangman." That spirit was contained there but was released by the witch and attacked the agents. They were able to escape but not defeat the Hangman which led to their final confrontation with the witch in the basement of the building. After much shooting, incantations, bible throwing, and a good amount of agent Amon's attempts at spiritual power, the witch was defeated.