Cronos begins with Fulcanelli, an alchemist who has fled the Spanish Inquisition for refuge in Vera Cruz, Mexico in 1536, only 15 years after the conquest of the Aztecs by Cortes. In this ancient land he continues his alchemical search, not for the means of converting base metals into gold, but for the elixir of life. Success comes with his invention of the Cronos device, a hand-held golden machine containing a mysterious insect which secretes a life-giving substance into a human host in exchange for blood. Fulcanelli lives another 400 years but dies when his heart is pierced by falling debris in an earthquake. Lying hidden within the base of Fulcanelli's wooden angel, the device makes its way into the present-day antique shop of Jesus Gris, a rather grey man surrounded by frozen clocks and the detritus of previous centuries. Dieter de la Guardia, a powerful but dying industrialist rather like Howard Hughes, is aware of Fulcanelli's life-giving object through his possession of a manuscript and frantically orders a search for the machine itself. However, having discovered the Cronos device and its ability to give him a more youthful appearance and renewed interest in life, Jesus Gris has no intention of giving it up for any sum. Thus begins the struggle between the powerful industrialist and the revived antique dealer over possession of the Cronos device.

As a teenager, Guillermo del Toro produced Super-8 films, but he could find no one to create the special effects that he needed. So, after studying theatrical makeup and magic and acquiring expensive equipment, he opened his own special-effects company, Necropia, in 1985 and created prosthetic makeup, puppets, and stop-motion animation for other directors' films. Meanwhile, he began his quest for Cronos.

His first version of the story was a script called Aurora Gray's Vampire, in which a little girl keeps her dead grandfather in a toy chest. Initially a vampire tale with the traditional blood transfusions, the story became richer through del Toro's study of alchemical history. He was also intrigued by Gerbert of Aurillac, a 10th-century French monk who created automatons before becoming Pope. The bug inside the Cronos device came about through his musings about a strange fad in Mexico in the 1970s when women wore live beetles pinned to their dresses as jewelry. From the barbarism of fashion came the idea of a captive bug that could extend life, but at a high price.

Casting began in 1990 and filming in 1991. Del Toro was blessed in his choice of Guillermo Navarro as director of photography and Tolita Figueroa, daughter of famed cinematographer Gabriel Figueroa, as production designer. Showing them some of the Terence Fisher horror films made for England's Hammer Films (Curse of the Werewolf, Curse of Frankenstein), del Toro secured their agreement regarding the look of Cronos. In brainstorming sessions, the three explored the effects of lenses, light, and film stock in relation to the objects, architectural lines, and colors Figueroa would use in the design. Consequently, del Toro achieved a very controlled environment which allowed many stunning compositions within the cinematic frame.

Alchemy played a large part in determining the film's colors. The director wanted the film to be "alchemically correct." Consequently, the color palette emphasizes black, red, gold, and white, each indicating a different state of purity of matter within alchemical lore, just as the protagonist moves toward a higher level of purity in his quest for self.

Another major visual influence on Cronos was painting, especially the works of the Symbolists, whom del Toro considers "very good at coding the colors and shapes of their paintings into stories." The late 19th-century Mexican painter Julio Ruelas (described by del Toro as "twisted and neurotic") first attracted his eye and then led him to Gustave Moreau and Carlos Schwabe, European Symbolists. In their works he found eroticism, rage, love, and mysticism as well as a wayof structuring color, shape, and line into meaning.

Drawing together such a rich diversity of images, colors, characters, and ideas, del Toro was able to realize his dream of making Cronos. The film was released in 1992 and garnered awards at Cannes and at the Ariel ceremonies in Mexico City. Subsequently, Guillermo del Toro has directed Mimic in the United States, and is currently at work on his next two projects.