S2E11 · Excelsis Dei

FBI agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) are called to the Excelsis Dei nursing home in Worcester, Massachusetts, in order to investigate a nurse's claim that she was raped by an invisible entity. Severely bruised, Michelle Charters (Teryl Rothery) claims that she knows who was responsible and names the attacker as Hal Arden, an elderly resident with Alzheimer's disease. When questioned, Hal admits that he made sexual overtures to Michelle but claims that it was harmless and that he is too elderly to have done anything. In turn, the hospital's administrator believes that Michelle has manufactured the rape allegation in order to extort money from the nursing home.

As Mulder and Scully investigate, they discover that many of the facility's Alzheimer's patients have shown significant improvement over their condition, a development that is not medically possible. Their doctor, Grago, attributes the patients' improvement to regimen he has applied using Deprenyl, an experimental drug that has so far shown negligible effect in patient studies. Before Mulder and Scully can make much headway, Hal dies unexpectedly while his roommate, Stan Phillips, stands by, complicating the investigation further. Worried about her father, Stan's daughter arranges to move him back into her home, despite his angry insistence that he doesn't want to leave. An orderly tries to help Stan pack, but Stan flees the room and leads the orderly on a chase to the roof. The orderly follows Stan out of a window but falls or is pushed to his death before Mulder can save him.

Mulder and Scully eventually discover that a Malaysian orderly, Gung Bittuen, is dosing the patients with an herbal drug made of mushrooms he cultivates in the building's basement. He explains that in Malay culture, the elderly are revered and treated with respect; coming to the U.S., Gung was appalled to see how Westerners send their elderly away to places like Excelsis Dei, where—as Gung has seen firsthand—they are badly mistreated. Gung attempted to ease their suffering with the herbal drug but admits something has gone badly wrong.

While the mushrooms are used in his country to "speak with the dead," the spirits lingering around Excelsis Dei are restless and angry, and the living residents' use of the mushrooms has given the spirits a power to act on that anger. The drug reverses the patients' Alzheimer's symptoms, but also allows them to channel the spirits, resulting in the assaults and murders.

As Stan, who stole all of Gung's herbal stash, overdoses and begins seizing, the spirits once again attack Charters, trapping her and Mulder in a flooding bathroom. Scully and Grago manage to stop Stan's seizures, at which point the spirits disappear and the bathroom door opens, freeing Mulder and Charters. The government of Massachusetts takes over the facility, and Gung is turned over to immigration services. The remaining original patients, no longer having access to the drug, revert to their previous state of dementia.