Dead in a Heartbeat

Dr. Gillian Hayes performs a high-stakes heart operation to save a patient, while a fellow doctor quietly questions whether the effort is worth it. The patient dies, and Hayes rails against the decision to abandon the procedure, feeling the loss on both professional and personal levels. A coroner's report hints that something explosive might be emanating from inside the chest, setting up a chilling clue.

Lt. Tom Royko questions Hayes in her office, and she fears she might be a suspect, though Royko insists she is not. The exchange plants the seed of doubt and foreshadows a larger investigation into the bombings.

A patient awaiting a pacemaker worries about what could go wrong during the procedure. Hayes reassures him that the operation is routine and safe, joking that she could perform it blindfolded, which unsettles the room.

The hospital receives a call claiming a bomb is in operating room #4, set to explode at 1:00. The clock shows about 12:50 as the surgical team prepares, and Hayes refuses evacuation while a colleague wonders if leaving is an option. The threat sets the clock ticking on a deadly trap.

With only Hayes and the patient remaining, Royko arrives to insist she step away and escort her out. Hayes resists, and Royko escorts her out just in time as the bomb detonates moments later—the device had been implanted inside the pacemaker Hayes had just inserted.

In the aftermath, Royko advises Hayes to assemble a list of ex-partners or others who might be suspects; Hayes learns she was initially on the list, but her decisive refusal to abandon the room helps her move off it. The near-miss sharpens the sense that the attack was personal and calculated.

A cellular phone found in a Federal Express package at Hayes's office broadcasts a countdown that correlates with a patient's heartbeat, suggesting the pacemaker is the trigger. Hayes and Royko hypothesize the countdown is synchronized to vital signs, and that removing the pacemaker without a substitute would cause a fatal explosion.

Benjamin McDonald is identified as the next target at the airport, and Hayes and Royko hurry to save him by moving him to a different room and attempting to remove the pacemaker with a simulator. When the simulator fails to arrive in time, Royko operates from a distance behind a shield as the pacemaker is detached and explodes, leaving McDonald to plead to his wife and children.

Hayes learns that Zachary Franklin is behind the bombs, driven by the death of his son during a prior surgery performed by Hayes. Franklin vows the next victim will be at an elementary school, escalating the danger and intensifying the mission to stop him.

Hayes and Royko discover a young patient at a school and rush to intervene. Royko triggers a distraction with a fire alarm while Hayes monitors the boy’s heart rate; the timer is not linked to heartbeat, so removing the pacemaker does not trigger an explosion. Royko shields the team behind a barrier as they evacuate the boy; Jessica Sara, a teacher and Hayes's former patient, falls victim when her chest explodes during the escape.

Franklin escalates the threat by leaving a birthday cake at Hayes's home for Sean, signaling that tomorrow he will kill 14 patients. Hayes and Royko race against time to prevent the new wave of attacks and to protect those at the hospital.

Clues point to Franklin's hideout near Hayes's office as the real plan unfolds, with Hayes and Royko closing in on the mastermind. The stakes rise as the hospital and community brace for the planned attack.

Franklin captures Lt. Royko’s son and implants a pacemaker linking Royko’s pulse to Hayes’s heartbeat; he commits suicide by leaping from the hospital roof, taking a bomb with him. Hayes and Royko sprint to the basement to save the boy, arriving just in time to prevent another disaster.

With the immediate threat neutralized, Hayes and Royko reflect on the narrow escape and the losses. The boy is saved, and the hospital begins to recover as they mourn Jessica Sara and the others lost in the chaos.