Tierney is a 29-year-old woman born into a prominent Irish crime family. She survives a highly traumatic childhood in a Siberian work camp and now masks her pain behind a defiant and combative exterior. She fiercely values her independence but finds herself constantly monitored and controlled by Achilles. When the rival families offer her up as a pawn in an arranged marriage to a Neapolitan mobster, Tierney must negotiate desperately for her freedom.

Achilles is the heavily scarred, volatile son of the Sicilian-American Ferrante crime family. Driven by a ruthless desire to succeed his father as the family leader, his primary vulnerability is his decade-long obsession with Tierney. He dictates who she can date and relentlessly monitors her daily life, framing his suffocating control as an extreme form of protection. When his father tasks him with delivering Tierney to another man to secure a political alliance, Achilles faces a direct conflict between his criminal ambition and his personal desires.

Tiernan is Tierney’s twin brother and a formidable enforcer for the Irish Mafia. Having endured a horrific childhood alongside his sister, his primary motivation is to shield his immediate family from harm. While fiercely loyal, his protective instincts sometimes manifest as controlling behavior, such as his misguided approval of Tierney's arranged marriage to secure a political alliance.

Luca is the eldest Ferrante brother and a primary enforcer of the Camorra's traditions. Emotionally detached and coldly pragmatic, he prioritizes the family's power and strategic advantage above all personal relationships. His ambition places him in direct competition with Achilles for the role of their father's successor, and he views his brother's obsession with Tierney as a dangerous liability.

Don Vello is the cruel and manipulative patriarch of the Sicilian-American Ferrante family. As he nears the end of his life, his primary focus is selecting a ruthless successor to maintain the family's dominance. He uses his children as pawns in his political games, deliberately testing Achilles's loyalty by ordering him to deliver Tierney to a rival mobster.

Enzo is the youngest of the Ferrante brothers, often masking the dark reality of his family's business behind a cheerful, outgoing demeanor. While he appears to be the most personable of the clan, he struggles privately with the rigid expectations placed upon him by the criminal underworld. He is willing to sacrifice his own happiness to maintain his standing within the ruthless hierarchy.

Tyrone is the head of the Irish mob and the father of Tierney and Tiernan. He is a selfish patriarch who made little effort to rescue his younger children when they were held captive in Siberia years earlier. In the present day, he continues to prioritize his own survival and criminal interests over the well-being of his surviving family members.

Known as "Lyosha," Alex is the head of the Russian Bratva. He spent his teenage years in Siberia, where he developed a complex and tender friendship with the captive Callaghan twins. Now a powerful crime boss in his own right, he manages the fragile political alliances between the Bratva, the Irish mob, and the Ferrante family while retaining a soft spot for Tierney.

Lila is the daughter of Don Vello Ferrante and the wife of Tiernan Callaghan. Her marriage to the Irish mobster provides a stabilizing presence for her husband. She remains fiercely loyal to her Ferrante brothers while supporting the political bridge created by her union.

Stefano Coppola is a ruthless leader of a rival Neapolitan crime clan within the Camorra system. Following a violent skirmish at a baptism, he leverages his position to demand Tierney Callaghan's hand in marriage as the price for peace, knowingly inserting himself into a volatile situation between the feuding families.

Tom Rothwell is a determined FBI agent intent on dismantling the Ferrante crime family. He views the internal conflicts and shifting loyalties within the mafia underworld as opportunities to gather evidence, making him a dangerous wild card for the warring clans.

Tristan Hale is a highly skilled hitman who frequently operates on the fringes of the mafia's conflicts. Known for his lethal precision, he is contracted for high-stakes assignments that the crime families choose not to handle internally.

Sofia is Luca Ferrante's wife. Trapped in a cold and transactional marriage, she finds little emotional fulfillment with her ambitious husband and remains largely oblivious to the dangerous politics swirling around her.

Jeremie is a Russian hacker and a member of the Bratva who frequently provides technical support and security for the Ferrante family. He is quietly observant and nurses a hidden affection for Luca's wife.

Katya is the sister of Bratva leader Alex Rasputin. Operating within the patriarchal structures of the Russian mob, she is utilized by her brother to forge political connections through arranged marriages.

Igor is the ruthless former leader of the Russian Bratva. Decades earlier, he abducted the Callaghan twins and subjected them to a brutal existence in a Siberian prison camp in retaliation against their father.

Francesca, known as Frankie, is the First Lady of the United States. Originating from a Mafia family herself, she maintains her friendship with Tierney and provides discreet assistance when her friend needs to vanish.

Gennaro, affectionately called Nero, is the infant son of Tiernan and Lila. His baptism serves as a violent initiation into the Ferrante family's deeply ingrained traditions.