Mulder and Scully's search for aliens takes a new direction in this cliff-hanger.

The episode begins with a narration by Scully describing planet Earth as seen from space, the beginning of life, and the series of mass extinctions that have happened in the past. Are we already on our way to another mass extinction? On the beach in Ivory Coast, a scientist examines a find - a fragment of a tablet with symbols on it, found in the sand. In his tent, he joins it with what appears to be another fragment of the same tablet. The two parts merge and the tablet flies across the tent, embedding itself in a Bible. As the scientist removes the tablet, the Bible opens to the Genesis verse that says, "And God blessed them and God said unto them Be fruitful and multiply and replenish the Earth..."

Three days later, the scientist, Soloman Merkmallen, is at American University in Washington DC. He meets Dr. Sandoz, who has reportedly found another fragment of the tablet, but Sandoz acts funny and Merkmallen suspects that he is an impostor. The real Dr. Sandoz arrives at the lab and finds Merkmallen dead on the floor, the tablet missing. Skinner briefs Mulder and Scully on their assignment to investigate Merkmallen's death. The body is missing, as is Dr. Sandoz. Merkmallen and Sandoz both believed in the theory of "Panspermia," that life on Earth originated from organisms that arrived from space. When Mulder sees a pencil rubbing of Merkmallen's tablet, he experiences a spell of noise, dissonance and mental disruption. On the way back to Mulder's office, Scully confesses that she no longer sees the need for Mulder's search for "the truth." He has exposed the global conspiracy and the conspirators are all dead. What more does he want? He replies, "My sister."

When Mulder and Scully visit Sandoz's lab, the impostor is there. He is the Biology Department chair, Dr. Barnes. He has made a career of exposing religious and spiritual fraud. When Scully shows him the rubbing, Mulder experiences another spell. Back at Mulder's office, Scully has brought "Chuck" in, an expert who has appeared in previous episodes. Chuck says the characters on the rubbing are phonetic Navajo, but since it was found in Africa it is likely a fake. Mulder wonders if it would be in Barnes' best interests to hide proof of the real thing. Mulder thinks Barnes killed Merkmallen. The agents visit the Sandoz residence in Maryland. They find a photo of Sandoz with Albert Hosteen and evidence that Sandoz has travelled frequently to Navajo country. In the kitchen trash compactor they find Merkmallen's body. They report to Skinner that there are traces of Cosmic Galactic Radiation in Merkmallen's remains, radiation found only in space that apparently came from the tablet. Mulder thinks Sandoz is innocent. His spells lead him to believe that Skinner is not telling them everything. When the agents leave Skinner's office, we see that Skinner video taped their meeting, and he gives the tape to Alex Krycek.

Scully tells Mulder to rest and she goes to New Mexico to find Albert. He is in the hospital and is being taken to treatment as she arrives. In his room she finds another copy of the rubbing. On the back is the verse from Genesis. Scully is told that Albert is dying from cancer. When Albert is returned to his room, Scully sees Sandoz and chases him. He says Albert was the only one of the WWII Navaho code talkers who would work with him. Scully cannot believe that an extraterrestrial artifact would have a Bible verse on it. Albert told Sandoz that Sandoz's fragment contained what appeared to be random letters. Meanwhile Mulder returns to American University and follows Barnes, experiencing additional spells. Finally he collapses in a stairwell. Krycek walks past him and approaches Barnes saying they are destined to become great friends. Scully telephones Mulder and Diana Fowley answers. Mulder is at home, resting. Mulder says that if Genesis really is written on the tablet, it proves that the origin of life on Earth came from space. Scully cannot accept that. After the call, Diana phones the Smoking Man to brief him, then she begins undressing.

Albert is taken into a Navajo tent for a traditional healing ceremony. Scully will not go in because she does not believe. Skinner phones her and says Mulder is in serious condition and that Scully should come at once. She arrives to find Mulder in the psychiatric ward, in a padded room. He is delirious with abnormal brain functions. Skinner seems to know details of Scully's investigation that she has not reported. Diana claims Mulder called her and said she was the only one who would believe him. Scully says "You're both lying." In Mulder's office, Scully finds a camera hidden in the ceiling. Sandoz calls - he has realised that the random letters on the tablet are gene sequences - a map to the human genetic structure. If only we could find more pieces... Scully hears a gunshot. Krycek has killed Sandoz.

On the beach in Ivory Coast 36 hours later, Scully is at Merkmallen's camp. His workers take her to another tablet found in the sand. It is much larger, and Scully realises it is actually part of a much larger structure, buried in the sand.