The film begins in 1536 with an alchemist creating a device that will give him eternal life. 400 years later we see the scene of a tragic accident where a vault had collapsed, one of the deceased was the alchemist, who had been pierced through the heart with a wood stake. His skin appears strange, non-human and a marble white color. At the alchemist's mansion is discovered blood being drained from a dead corpse. The cronos, which the alchemist created for eternal life is not documented in the sale of all of his possessions, including his home, and the basins of blood discovered in the home were never revealed to the public.
In the present day, we find Jesús Gris, an antique dealer who is married to Mercedes. They look after their deceased son's daughter, Aurora. At his shop, Jesús has a strange man come into his shop looking at statues by peeling away their wrappings. The man leaves after he sees one in particular. Later, Jesús, while putting a puzzle together with Aurora finds cockroaches pouring out of the statue and he finds there is an opening at the bottom with the cronos inside. He has no idea what it is and thinks its merely a funny toy until it's razor sharp stingers pierce into his skin.
Later in the night Jesús has uncontrollable itching and pain that is only alleviated when the cronos is reattached to his body, allowing the device to drain his blood. We then are introduced to Angel, who is the nephew of De la Guardia, a very sick man who is in search of the cronos. Angel purchases the statue from Jesús not knowing that the cronos has been taken out. Jesús' health and strength are increasing in the meantime. Aurora recognizes something is wrong and hides the cronos.
Once De la Guardia learns the cronos is missing he has Jesús' shop vandalized and leaves his card. Jesús visits De la Guardia's factory after he convinces Aurora to give the cronos back to him. Here the dying man explains to Jesús that an insect lives inside the cronos and it feeds on Jesús' blood while at the same time providing eternal life to the human being it feeds upon. It is said that the bug relates to immortality and holy people including Jesus Christ. Jesús leaves the cronos with De la Guardia, or so the man thinks. It is only two steel padlocks.
While Jesús, Mercedes and Aurora are at a party for New Year's Eve Jesús begins to have a thirst for blood and follows a man into the bathroom who has a nosebleed. While licking the man's blood off of the floor, Jesús is knocked unconscious by Angel who ties him up and tries to get the cronos from him, but Angel won't tell him where it is. This leads to Angel knocking Jesús out once more and pushing him off a cliff inside of his car. Mercedes has a funeral for Jesús, body and all, but right before he is cremated, Jesús escapes from his coffin. Believing Jesús to be burned, Angel returns to his uncle telling him that Jesús is dead.
Jesús wanders in the night until he finally returns home where Aurora is waiting for him with a towel. She helps to hide her grandfather, giving him her toy chest to sleep in like a coffin and helping him to compose a letter to his wife explaining everything. Jesús and Aurora go to De la Guardia's factory in search of the alchemist's text and De la Guardia catches them with the book. He promises Jesús to give him a way out of what is happening to him if he gives him the cronos. Jesús does and De la Guardia stabs him which leads to Aurora smashing him over the head with his own cane. Jesús then drinks De la Guardia's blood before Angel comes.
Upon seeing his uncle still alive, Angel crushes his neck, killing him then begins to chase down Jesús and Aurora to the building's rooftop. But, Jesús unexpectedly grabs the much stronger Angel and jumps off the roof knowing that Angel will die and he will only be in pain. Aurora runs to the ground and places the cronos on her grandfather and he comes back to life. He is enticed by the blood on his granddaughter's hand and nearly beings to feed from her, but he fights off his urge and destroys the cronos.
Jesús is then seen in his bed at home. Aurora lays her head upon her grandfather's skin which has become the same marble-white color as the alchemist's at the beginning of the film. We see the sunshine gleaming through the window as Mercedes comes to her husband, embracing his hand as the camera fades to black.
