Johnson begins Soul by Soul by discussing the chattel principle, which based a slave's identity on their market value. He claims that the slave market would not have existed if it did not have roots within American culture.

The second chapter examines the life of a slave trader, such as their roles and responsibilities. Johnson also tells of the bond among slaves brought to the market.

Chapter 3 focuses on the culture that created slave markets, especially the fact that slave trading was an economic staple in the South. This allowed slave owners and traders to justify the act, as the financial success of the region depended on human trafficking.

Chapter 4 examines how enslaved people were dehumanized and viewed as property. Johnson argues that this rhetoric created a slave-trading culture that allowed brutal mistreatment.

Chapter 5 explores the influence of race in the creation of slave-trading culture. To do this, Johnson again refers to rhetoric, as well as the belief by many in slave states that physical features determined character and personal value. The key argument in this chapter is that biological racism aided in the creation and success of slave markets.

Chapter 6 discusses the logistics of a slave market, claiming that each slave up for sale was given a role to play, as if it were a performance. The book ends by explaining life after an enslaved person was sold at a market, such as the need to adapt to a new master, meager or no pay, and violence.