Ciudades en Sombras was penned in Mérida, Mexico in 1685 by a Guatemalan clergyman of mixed Mayan and Spanish ancestry named Encero Hurtado. Early in his career, Hurtado claimed to have been captured during an uprising of Maya against the Spanish. After the rebellion was crushed, he claimed to have dwelt among a break-away faction of Itzá Indians. There in a hidden city built upon an ancient temple complex in the jungles of Guatemala, he served for some 30 years as a scribe among the Itzá priests. 

Not long after appearing in Mérida and penning his manuscript, Hurtado was imprisoned by the Mexican inquisition. History records that the elderly clergyman died before sentence could be passed, though legend has it he vanished from his cell one night. A small New World print run is said to have been supressed by authorities, leaving no known copies of this edition.

In Seville, Spain, Hurtado's work was published in 1712 as a hefty quarto bound in thick, red-brown leather. Six of these are known to exist in major museums, with others probably existing in private hands. An expurgated and faulty English translation (sensationally subtitled "Lost Empire of the Maya") was published in San Francisco in 1862 and dismissed by Meso-American scholars as the lurid imaginings of a crackpot or charlatan. A score or more of these green octavo volumes might still exist by the 1920s.

Hurtado writes of ceremonial chambers hidden beneath ancient pyramids, and of shadowy beings which creep up from caverns below to partake in the rituals that unfold there. He describes out-of-body, shamanistic journeys and communication with spirits. He obsesses over openings to the underworld (such as one said to exist in a cave near Coban, Guatemala) and the great secrets to be learned by mortals daring enough to brave these fearful portals. The Seville printing contains several passages in which Hurtado transcribes supposed Mayan ritual chants. These are missing from the English language edition.

Ciudades en Sombras, by Encero Hurtado, 1685
Spanish language, -1D6/1D10 sanity; +10 Mythos; Spells: See below; 7D6 weeks (average 24 weeks) to study and comprehend

Cities in Shadows: Lost Empire of the Maya, translated 1862
English language, -1D3/1D6 sanity; +6 Mythos; No Spells; 3D6 (average 10 weeks) to study and comprehend

Spells: The English language edition contains no spells. The Seville printing contains the following:
Litany to the Lord of the Underworld (Contact Tsathoggua), Invocation of Daemons (Contact Formless Spawn), Descrying the Passage (Find Gate), Speaking with the Dead (Command Ghost), Spirit Journeys (Brew Dream Drug), Confronting Hostile Spirits (Snare Dreamer), Binding of Spirits (Bind Soul)

Other Benefits: The keeper may wish to grant the reader an Anthropology skill check.