Mulder and Scully are on a stakeout, looking for a "mystery woman" who's involved with street people. Mulder gets a phone call, and departs without explanation.

Skinner tells Mulder about the disappearance of a woman from her Vermont home, and asks the agent about the "mythical or paranormal" significance of ravens, which were observed before the disappearance.

Vermont. The town. Mulder drives up, meets Phil, a local policeman. They meet Michele, the young girl who had seen the ravens, and Howard, the father, who is a judge and has just returned from a trip. There's no sign of the mother -- but Howard has found birth control pills, and (having had a vasectomy) suspects his wife of having an affair and running off. He's also found an unidentified key.

Mulder stays with Ellen and Phil. She makes good meals, is a very gracious hostess. Scully, meanwhile, is still stuck in the comfortless stakeout.

A raven shows up outside Howard the judge's house. Sticking up from the ground are human fingers. His wife has been found. Phil doesn't think Howard did this. Mulder agrees, and tells the skeptical cop about how mirrors may be doorways to the spirit world.

Ellen is sweeping her tidy home, and finds a key. Awk! A raven is in the house. There's a smashed mirror and hairy intruder. But Ellen hides in a closet with her baby. No one is hurt.

Night. A lodge with many cabins. Phil is there, shifty-eyed. He meets Jenny, with whom he's having an affair. There's a mirror on the ceiling.

Mulder enjoys a hearty breakfast, prepared by Ellen. But he's getting suspicious of Phil., who was out all night. He asks for Phil to return a piece of evidence -- the first key -- and Phil complies.

Back at the lodge, Jenny sees a raven outside her window. The ceiling mirror shatters and she's suddenly grappling with a hairy intruder. She manages to stick a shard of glass into the intruder's shoulder blade.

Jenny is dead. The cops are there. So is Mulder. Phil admits he saw Jenny last night -- but says she was alive when he left her. The cop, less skeptical now, wonders if maybe Mulder's right that a spirit entity has been called forth -- inadvertently, perhaps.

Back home, Ellen notices she has a wound on her shoulder blade. She flashes back to a fight with Jenny.

Mulder enters the house, calls to Ellen. But she's in the bathroom, forlorn, and soon turns into the hairy attacker. There's a struggle, and soon Mulder's head is submerged in the bathtub. But his attacker relinquishes her -- or its -- grip, and Mulder sees Ellen lying sadly on the floor.

Jail. Ellen is in a cell. Mulder and Phil talk. It seems the cop had wanted out of the marriage, even without knowing his wife periodically turned into a hairy beast. Their future is not exceedingly bright.

Silently, Ellen stands in her cell and looks out the window. There's a raven sitting there.