Steve is the fire chief at the Clover Hill Nuclear Power Plant in Waketa. Dealing with the recent loss of his wife to cancer, he struggles to raise his young son. When a commercial airplane crashes into the plant, Steve steps into a leadership role to handle the crisis. He tends to compartmentalize his personal pain by throwing himself entirely into his professional duties.

Joss is a regional representative for the Nuclear Emergency Support Team. Originally from Waketa, she moved away to pursue a career in Washington, D.C. before returning to her hometown. She approaches the nuclear crisis with a broad, statistical mindset. Her pragmatic approach frequently puts her at odds with local leaders who prioritize immediate safety over national calculations.

Ethan is the manager of the Clover Hill Nuclear Power Plant. Following the plane crash, he works to assess the damage and organize the remaining plant personnel. He prioritizes the immediate safety of the Waketa residents, including his own family. His protective leadership style contrasts with those who favor making broad, theoretical sacrifices.

Dani is a brave firefighter for the Waketa Township Fire Department. She is a single mother to her five-year-old daughter. During the chaos of the crash, she encounters a trapped child and disobeys direct orders to report to the power plant. She chooses instead to focus her efforts on a single, highly dangerous rescue mission.

Matt is Steve's preteen son. Struggling with the recent death of his mother, he acts out rebelliously at school and feels disconnected from his father. During the community evacuation, he disobeys safety instructions and uses his personal drone to investigate the damage at the power plant.

Marion is Dani's father and a retired nuclear plant worker. Possessing valuable knowledge about the plant's older infrastructure, he takes charge of protecting his granddaughter. He quickly becomes a vital communication link, using an old CB radio to coordinate evacuation efforts across the community.

Levon is a firefighter with the Waketa Township Fire Department. He works alongside Dani during the initial response to the plane crash. He supports Dani's decision to attempt a risky rescue on the bridge. This decision shows his loyalty and commitment to helping individuals in immediate danger.

Carla is a schoolteacher at Carter Valley Elementary and Levon's wife. When the disaster strikes, she helps organize the evacuation of her students. She manages her own personal grief while working to protect the children in her care and assist the wider community response.

Michael Dawson is the President of the United States. Forced into an underground command center, he oversees the national response to the potential nuclear meltdown. He relies heavily on cabinet members and experts on the ground to gauge the catastrophic economic and environmental implications of the crisis.

Connor is a five-year-old boy who survives the initial impact that kills the rest of his family. Suspended dangerously over the Mississippi River, he relies on the local firefighters to keep him calm. He must bravely follow their instructions as conditions around the vehicle deteriorate.

R.J. is a local trucker and former boat repairman. Disillusioned by past experiences with the government, he is initially hostile and reluctant to assist the authorities with the nuclear crisis. However, his specialized equipment and skills make him a valuable asset to the community's localized rescue operations.

Chief Loftus leads the Waketa Township Fire Department. He represents a pragmatic approach to crisis management, ordering his personnel to prioritize the power plant over individual emergencies. His directives emphasize making hard choices when resources are severely limited.

Reverend Michaels is the pastor at United Grace Church in Waketa. He views his congregation as a large, interconnected family. Following the disaster, he transforms his church into a central hub for community resilience, organizing supplies and evacuation logistics for the townspeople.

Paul is Connor's father. While driving his family's minivan, he encounters the falling wreckage of the airplane. He uses his final moments of consciousness to comfort and instruct his surviving son before succumbing to his injuries.

Valerie is Paul's wife and the mother of Connor and Caity. She is killed instantly when the commercial airplane wing crushes their vehicle on the bridge.

Caity is the daughter of Paul and Valerie. Like her mother, she is killed instantly during the initial collision with the falling airplane wing.

Bri is Dani's five-year-old daughter. While her mother is deployed to the crash sites, Bri is evacuated from Carter Valley Elementary by her grandfather, remaining a central motivation for Dani's survival and heroism.

Claire is Steve's late wife and Matt's mother. Her recent death from cancer casts a heavy shadow over her family, heavily influencing Steve's emotional distance and Matt's rebellious behavior during the unfolding crisis.

Tony is the White House Chief of Staff. He coordinates the immediate executive response from an underground bunker, keeping the President informed of the rapidly deteriorating situation in Minnesota.

Frankie is a firefighter with the Waketa Township Fire Department. Initially siding with Chief Loftus's orders to abandon the trapped civilian, he eventually agrees to stay and help his crew attempt the rescue.

Boggs is a local firefighter who believes his primary duty is to help people directly in front of him. He voices his support for Dani's rescue operation, bringing specialized tools to assist in breaching the trapped vehicle.

Renee is a fluid-dynamics engineer at the power plant. She proposes the initial theoretical solution to patch the leaking spent fuel pool, kicking off the search for specialized welding equipment.

George is a firefighter assigned to the nuclear power plant. He operates the electricity controls and safety lines while Steve attempts a highly dangerous underwater welding repair.

Vikram is an employee at the power plant working in the control room. He provides critical data updates to the management team as they assess the damage from the plane crash.