The the leader, Raoul LaValle, learns that she's a chemist, he informs her that his marijuana fields are infected. People who have come in contact with he plant are infected by a flesh eating toxin that brings a miserable death within nine days of exposure.
La Valle also deals in body parts and tells Emma that she must find a cure or be killed. Additionally, his mistress has been infected and he believes that the fungus came because the United States was spraying his fields to destroy the marijuana. Because of he need for revenge upon someone, he informs Emma that if she doesn't find a cure, he'll ship the next contaminated batch to the United States. He wants to spread disease to pay the United States back. He will also begin selling contaminated body parts to further infect people in the United States.
Emma is an ultra marathon runner and feels that she can escape and inform the authorities but she feels sympathy for the migrant workers who are forced to work in the fields and harvest the infected plants and she wants to save them.
She comes in contact with a college drop out, Oz Kroger who wanted to transport some drugs to earn money but is a man of conscience and when he sees the disease the plants carry, he decides that he wants to help Emma.
The story is well told, and the author provides enough evidence about chemistry and disease that the reader is convinced of the possibility of this really happening.
The drug dealers are truly villainous and the author gives a good point that in Mexico people really don't know who to trust. Were authorities acting on their own or are they hired by a competing cartel in order to take over the first cartel's drug operation.
The concept of the novel is original but the plotting could have been a bit stronger as Emma attempts to make her escape and a cat and mouse game begins. However, the reader does become emotionally involved and lost in the action as the chase is for life or death.