Cathy Ames reemerges as Catherine Amesbury after setting fire to her parents' house and leaving them for dead. She approaches Mr. Edwards, who runs a prostitute ring in New England, seeking a job. His devout wife believes that he runs a respectable business; at home, Mr. Edwards is the epitome of the middle-class family man. Mr. Edwards is shocked by Cathy's request, because she is far more beautiful and upscale than the other women who work for him. He treats his employees poorly, and controls them with an iron fist. However, for the first time in his life he falls in love: he becomes obsessed with Cathy and takes her as his mistress, buying her a luxurious house. However, when he comes to realize the extent of his dependency upon her, he has her investigated and learns about the suspicious nature of the fire that killed her parents. At this point, he comes to see her true nature. One evening, he takes her out into the country, beats her almost to the point of death, and leaves her near the Trask farm.
Although they never need to work, Charles and Adam maintain the Connecticut family farm, constantly bickering amongst themselves over silly, inconsequential things such as what time to set the alarm clock, or what to cook for dinner. One day, Adam leaves in a huff, travels to South America, and returns to find an even larger farm. Charles now works on from sun-up to sun-down. Soon afterwards, they find Cathy unconscious on their back steps. Despite Charles' protests that it would be unseemly for two single men to house a single, unrelated woman, Adam nurses her back to health. Soon, he finds that he has fallen deeply in love with her, and asks her to marry him. When the sheriff hears about her broken bones and bruises, he calls to question her, but she feigns amnesia. Charles is one of the few characters who can clearly see through Cathy's wiles, and she fears him for it. He becomes furious when Adam announces their engagement. On their wedding night, Cathy drugs Adam with the opiate medication she has been taking for pain, and seduces Charles. Charles, who puts up no resistance, calls Adam a "poor bastard" as he takes his brother's wife into his bed. A short time later, Adam and Charles move to California.
In the transitional chapter before Adam and Cathy Trask take up residence in the Salinas Valley, the narrator looks back from the beginning of the twentieth century, pondering humanity's ability to view history through rose-colored lenses and failure to recall disagreeable historical facts. He summarizes the previous century as: "boom and bust, bankruptcy, depression." People either idealize the past ("the old time, the gay time, sweet and simple, as though time were young and fearless") or they say "good riddance," and look eagerly forward to "this clean new hundred years." It is this tendency to forget, he continues, that enables the progression of the human race. He goes on to declare that the nineteenth century was an era of chaos, and predicts that the advance of automation during the twentieth century will result in a loss of creativity on the individual level. "Monstrous changes," he states, "are taking place in the world, and mass culture will deeply affect the individual mind, which will be caught up in the collective mentality: when our food and clothing and housing are all born in the complication of mass production, mass method is bound to get into our thinking and to eliminate all other thinking." Only individuals, he holds, can create; groups of people have never created anything. The most valuable thing in the world, the narrator believes, is the individual mind.
Before they leave for California, Adam buys out Charles' share of the family farm and moves with the reluctant Cathy to the Salinas Valley, in California. Adam remains blind to the evil that permeates Cathy's being: he views her as "a sweet and holy girl, precious beyond thinking, clean and loving." To her dismay, Cathy discovers that she is pregnant - a condition she finds absolutely abhorrent - and attempts to abort the baby herself by using a knitting needle. She fails in her attempt, and lies to the doctor, saying that she is terrified of passing along epilepsy to any offspring. The doctor informs Adam of Cathy's pregnancy, and he practically leaps with joy. Finally, he is happy, and feels that life is worth living. Full of hope, he goes about setting up a ranch so that he can gain from the rich opportunities all around him. Samuel Hamilton comes to help Adam locate a ranch with water. Like his biblical namesake, Adam is intent on building a garden in his new-found Eden: "I mean to make a garden of my land." Samuel is a diviner with an almost preternatural ability to locate water. While they explore the Salinas Valley for the most fertile piece of land available, Samuel and Adam form an instant friendship that will last a lifetime. At Samuel's prompting, Adam buys the old Sanchez place, located near King City.
In chapter 14, Steinbeck departs from the intertwining Hamilton and Trask family narratives to honor the schoolteacher Olive Hamilton: one of Samuel Hamilton's daughters, and Steinbeck's real-life mother. The wife of a flour mill owner, Olive sells the most Liberty bonds during World War I, and earns the grand prize of a ride in an airplane. The young mother is terrified, and absolutely convinced that she is going to die. She prepares for her death by completing any unfinished business, burning letters, and donning new underwear. Olive willingly undergoes all of this mental torture simply to make her family proud. She sits in the seat behind the pilot, and they take off, to her children's absolute delight. When the pilot suggests some daredevil maneuvers, Olive cannot hear him over the noise, and just waves and smiles in acquiescence. No matter what type of stunts the pilot practices, she merely smiles. Underneath the smiling veneer, however, she is in shock, and is nearly catatonic when she comes back down to earth. Her trip turns into a much-repeated family story.
Steinbeck takes back up the threads of Adam and Cathy Trask's story in chapter 15. Sadly deluded by his wife Cathy, Adam continues to find happiness on his new California ranch, and eagerly looks forward to the birth of his first child. He has almost forgotten the dark days he spent on the Connecticut family farm, and no longer corresponds by mail with his brother Charles. His Chinese-American servant, Lee, becomes indispensable to him. Cathy doesn't like Lee, but realizes how invaluable a good servant can be and puts up with him. Like Samuel Hamilton and Charles Trask before him, Lee can see through Cathy, and since she cannot control him, she fears him. Lee speaks in a degrading stereotypical Chinese pidgin dialect and wears his hair long despite his university education simply because Americans expect him to do so. Americans look at him suspiciously if he speaks as they do. The dialect helps to keep him from being singled out; in a sense, it makes him invisible. Lee also becomes fast friends with Samuel Hamilton who, since both men are immigrants, treats him as an equal. Lee explains to Samuel the pride he takes in his choice of occupation: "A good servant, and I am an excellent one, can completely control his master." Samuel accepts Adam's proffered invitation to dinner at the ranch, but leaves in a hurry when Cathy doesn't speak. Something, he realizes, is very wrong, yet Adam sits at the table as if all is normal, completely enthralled with his beautiful wife. After Samuel leaves, Cathy announces to Adam that she plans on leaving him as soon as possible after giving birth. Adam, believing that pregnant women have silly ideas and that all will be well once the baby arrives, dismisses her announcement.
For Steinbeck, East of Eden was an experimental work of fiction which intertwined the strands of two family narratives, with chapters on philosophy and family history. He received both negative criticism and high literary acclaim from scholars for this methodology. So, while the structure may initially seem choppy and the timeline difficult to follow, readers may eventually come to recognize Steinbeck's vision and begin viewing the novel in terms of its organic unity.
While Charles and Adam represent the biblical brothers Cain and Abel, Cathy Amesbury, whose new name suggests that her evil "aims" have been "buried", represents Satan, who tempted Adam and Eve to eat the apple from the tree of knowledge in the Garden of Eden, despite God's injunction against such an action. Cathy tempts Adam Trask sexually until he marries her, and shortly thereafter, she causes his downfall. Cathy and Charles hate each other, each recognizing the evil inherent within the other. In this manner, they are kindred spirits. Cathy's behavior is unsurprising given her past actions against her parents, friends, schoolteacher, and Mr. Edwards, but Charles' betrayal of his brother demonstrates his profoundly evil nature. "I think you are a devil," he states earlier to Cathy. Clearly, when Charles accepts his brother's wife into his bed on Adam's wedding night, he is, in effect, sleeping with the devil.
In the transitional, highly philosophical chapter 12, Steinbeck insists on the primacy of the creative power of the individual mind, and warns of the danger of following the impulse of the destructive crowd. The power of the individual mind is, he maintains, indomitable. Although it will not be apparent for awhile, here Steinbeck lays the foundation for one of the novel's major themes - the issue of free will. Are people, he wonders, born with an innate predisposition towards good or evil, or do they have the ability to choose between the two extremes? Forgoing predestination, he leans toward the primacy of individual choice; hence, he develops his fear that the individual mind will be caught up in the threatening collective mentality.
Steinbeck moves - somewhat awkwardly - from this philosophical section of the novel to a eulogy in praise of his mother. Although the chapter concerning Olive Hamilton seems out-of-place because it is "out of time" in terms of the chronological narrative, Steinbeck has a two-fold reason for placing it in this section of the novel. Besides honoring his mother, the author juxtaposes the good mother, Olive, who would die rather than disappoint her family, with the evil mother, Cathy Trask. Olive comes from the fertile, fun-loving, happy Hamilton family, and becomes the highly efficient, loving mother of the four Steinbeck children. She is very much like her mother, Liza Hamilton. Cathy, on the other hand, murders her parents and attempts to abort her first child. One of the novel's themes, fertility versus barrenness, resonates in the juxtaposition of these two female characters. Thus, the admirable Olive Hamilton acts as a foil for the deviant Cathy Trask in same manner as the servant Lee, who will come in time to serve the twins in a maternal capacity.
The Chinese-American Trask's servant, Lee, is in fact a philosopher in disguise. An extraordinarily deep thinker, he sees through people without being observed, and acts as a foil to the novel's evil characters, especially Cathy. Steinbeck also takes this opportunity to shed light on the plight of Asian-Americans, who have a considerably difficult time assimilating into mainstream American culture.