Tunguska is an actual place in Russia where a massive meteorite crashed on June 30, 1908. Mystery still surrounds the meteorite explosion today. It is from this event that Chris Carter has created the sixth file, Tunguska.
While examining an ancient rock, a government scientist is exposed to a mysterious, black fluid that causes him to lapse into a coma. FBI agent Fox Mulder believes the substance may be extraterrestrial in origin. As Mulder and his partner Scully probe further, they meet up with Alex Krycek - the rogue operative linked to the murders of Mulderís father and Scullyís sister. Krycek holds the key to unlocking the mystery surrounding the rock. But when the search for answers leads to a remote forest near Tunguska, Russia; Mulder will come face to face with the startling depths of Krycekís deception.