One certain case seems to have the FBI completely baffled. Four African/American men have disappeared off the streets of Philadelphia and the latest case involves the victim lacking in pigmentation which is something that no one has ever seen before. They call in Scully to try to get her to help them resolve this mystery.

Mulder carries out his own investigation and it leads him to find out about a cover-up much similar to the death they are investigating aboard a plane from West Africa where they found a presence of a native plant common to that area. Scully's investigations lead her to find out that the victim's pituitary gland (produces melanin) had been completely destroyed.

Meanwhile, the killer is at it again and his latest victim is a young black student who he follows after leaving a bus stop. The agents investigate the evidence left at the crime scene and track it down to Samuel Aboah, a West African immigrant. They locate and arrest him and after a hospital tests him they find that he is actually missing a pituitary gland.

Marita Covarrubias (Mulder's latest informant) again shows up directing Mulder to a diplomat from West Africa, Minister Diabara. He explains to Mulder that he ordered the cover up of the first murder because he knew the killer's identity, the legendary Teliko which is an evil spirit that sucks the life of their victims at night. That is why he had covered it up, it would have sounded absolutely ridiculous. Mulder though, is ready to except his bizarre theories. Mulder reports what the Minister told him to Scully who is as always skeptical but tells her that the Teliko are actually members of a lost African clan who hunt down victims so they can steal their pituitary glands which they are lacking in.

Meanwhile, Aboah escapes from the hospital and in what looks like a scene taken directly from Tooms, Mulder manages to track him down but is captured by him. Scully is armed and ready and shoots and kills Aboah before he can kill Mulder. The real truth about the Teliko will now never really be known.....