Though this thriller takes place in Brazil, its appeal is universal, so well-executed and its protagonist so accessible and relatable that cultural differences are irrelevant; the unpredictability of human nature has no borders. The protagonist, Zico, is a contract killer, a young man raised in poverty and violence, with only an older sister to care for him. After the brutal murder of his sister, Zico by necessity closes off his heart, earning money to survive any way he can. Everything changes when he falls in love with a village girl, Daniella. Craving another life, Zico decides he is through with killing, ready for a future with Daniella.

Unfortunately, he has not taken into consideration the pressure from the local crime boss, Costa, who pays his most reliable assassin for targeted killings. He encourages Zico to carry out “one more death”: Sister Delores Beckett, an American nun in Brazil to work with the disenfranchised. Sister Delores entreats the poor to throw off the yoke of their oppressors, wealthy opportunists who rape the land of natural resources and exploit cheap labor, leaving barrenness and destruction in their wake. Though a single woman of God, her words are powerful. Zico is sorely tempted by Costa’s offer, the sum enough to start over with Daniella, even the deed to a piece of land in his name. The young man seriously considers the assassination but has not fully committed when he goes up river with Raul, an old man and his only other friend besides Daniella. Zico agrees to assist in the pickup and delivery of a shipment of goods. Such river runs are common practice, desperate people facilitating the movement of illegal items from one point to another--sometimes guns, sometimes drugs--always dangerous but financially rewarding.

Things take a turn for the worse when Leonardo, a handsome thug, demands passage to protect his interest in the delivery and payment after delivery. Zico becomes increasingly uncomfortable with the complications, Costa making it clear that if he fails to accept the assignment, Daniella, Raul, and Raul's wife, Carolina, will be at risk. Two of Costa’s “soldiers” stand guard to ensure Zico’s cooperation. After a fight with her mother, Daniella demands to go with Zico, the journey--and his decision--made more dangerous by conflicting agendas and the potential for trouble. Carrying out the assassination will be much more difficult with his watchful girlfriend’s presence.

Zico wants only to keep Daniella and Raul safe. The old man’s boat carryies four passengers in a confined space, the river always treacherous and unpredictable. Though warned against encouraging Leonardo’s overtures, Daniella refuses to listen, thinking the other man harmless--until she learns otherwise. It is on the journey upriver that the heart of this drama resides, unexpected circumstances and rising tempers contributing to confrontations between Leonardo and the others. Increasingly anxious, drunk, and drugged, Leonardo sheds congeniality for violence and threat, desperate to deliver his goods on time. Meanwhile, Raul is in the grip of a fever that grows worse as the days pass. Zico is frantic to protect his lover and friend from the volatile passenger, Leonardo’s impulsive actions putting them all at risk: “Death’s shadow grew a little longer.”

The passengers survive the rigors of the voyage, the sudden storms, and the threats, Leonardo on the edge of violence as they move along the river, Raul sickening. Zico imagines that one more killing can buy his freedom from this life. Then fate--and a grounded vessel--deliver Sister Delores to Raul’s boat (aptly named “God and the Devil”), forcing Zico to examine his life and the values he has chosen. Smith layers events and personalities, including the stubborn altruism of the nun, his protagonist gaining insight into his present and future. His choices limited by poverty, Zico faces a momentous decision, an internal war between what is and what can be. Richly atmospheric, capturing the struggle to dominate a land of enviable resources, The Darkest Heart is poignant, troubling and ultimately profound, the river a metaphor for the unpredictability of life. Zico is a man on the cusp of redemption: “There was so much life and death, even in the places where light can never reach.”