The episodes follow the investigations of paranormal-related cases, or X-Files, by FBI Special Agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson).
Investigating evidence of an alien autopsy, FBI special agent Fox Mulder (David Duchovny) infiltrates a secretive government train carriage carrying an alien-human hybrid.
[8][9] Covarrubias' aid is sought when Mulder attempts to reach Tunguska in Russia to investigate the source of a further black oil contamination.
Writer John Shiban felt it was natural creating an arms race-like story between the United States and Russia, being that the Cold War had ended a few years earlier.
[19] The inspiration for the oil-containing rocks was NASA's announcement of possible evidence of extraterrestrial life in the Allan Hills 84001 meteorite; while the gulag scenes were based on Aleksandr Solzhenitsyn's books The Gulag Archipelago and One Day in the Life of Ivan Denisovich[20] The on-screen appearance of the black oil was achieved through visual effects; the shimmering oil effect was digitally placed over the actors' corneas in post-production.
[19] During the filming of "Apocrypha", Nicholas Lea was fitted with a mask with tubes for the scene where the alien black oil leaves his body.
[22] The show's producers decided to give Gillian Anderson's character Dana Scully cancer early in the fourth season.
Carter felt the move would give the show an interesting platform on which to discuss things such as faith, science, health care and a certain element of the paranormal.
However, Frank Spotnitz felt that, given the appearances of cancer-stricken abductees in previous episodes, it was an "obligatory" move to have Scully follow suit.
Slant Magazine's Keith Uhlich rated it three-and-a-half stars out of five, noting that there is "an unabashed confidence to these episodes", although this "comes with something of a price as the thrill and surprise of season two mythology stories like "Colony" and "End Game" are replaced by a nagging suspicion that the writers are starting to tread water".
She too felt that the interrupted nature of the episodes caused a lack of "believable" pacing, and noted that the release "feels like a blatant cash grab by Fox to milk an old franchise while they still can".