The premiere of "Zero Day" kicks off with an intriguing flashforward, depicting Former President George Mullen struggling to unlock his safe. In a moment of frustration, he inadvertently shatters a photograph within, revealing an image of him donned in a uniform alongside two companions, dated April 29, 1975. As the safe finally yields to his persistence, a mysterious figure steps into view.
Three days prior, George embarks on his usual morning ritual, amidst the backdrop of his wife's impending appointment to the appellate court and a strained relationship with his daughter, Alex, whom he had tried to dissuade from pursuing a political position.
His initial meeting of the day is with a ghostwriter tasked with bringing his memoirs to life. A publication deal is already in place, yet George has been procrastinating on the initial draft. Ben, the editor, pressures the ghostwriter to expedite the process, emphasizing the significance of George's narrative as the only president to garner bipartisan support.
The ghostwriter's eyes fall upon the 1975 photograph, prompting a revealing discourse. One of the men in the picture, John Flanagan, was George's childhood friend, killed post-discharge, an event that fueled George's aspiration to become a prosecutor. Despite being assured of reelection, he famously declined to run again. The ghostwriter suggests that unsavory rumors surround this decision, which George could silence through his memoir. However, when she inadvertently mentions his deceased son, George loses his composure and summarily dismisses her.
She promptly calls Ben, speculating that George remains haunted by his reelection decision and hinting at a deeper, untold trauma. Suddenly, the car phones go dead, displaying a chilling message: "This will happen again." Amidst the ensuing confusion, a train veers onto the wrong track, fatefully colliding with their vehicle, creating a cliffhanger that propels the narrative forward.
The newscasts detail a cyber onslaught that plunged the nation into darkness, triggering a cascade of disasters: airplanes plummeting from the sky, subway trains colliding, and medical devices frying in their circuits. Within the Russian Consulate in New York, tensions escalate as an individual seizes a firearm, while Speaker of the House Dreyer frantically crafts a reassuring message. It is now Day 1 of the post-cyber attack era, a day designated ominously as Zero Day. Shadows lurk in the forest, prompting George to instruct the caretaker, Hector, to lay animal traps as a precaution.
The media storm surrounding Zero Day's aftermath intensifies, highlighting missing persons and a colossal data breach that has left the country vulnerable. Roger, a representative from the White House, arrives with an urgent proposition for George: to provide a morale boost and quell the public's rising panic. Though hesitant, George relents after Roger assures him that it will merely involve a 30-minute public address.
At a rescue site, George arrives with purpose, allocating resources and directing efforts with precision. The local populace, frayed and suspicious, murmur theories of insurance fraud and conspiracy. Tensions flare into physical altercations, prompting George to intervene. With empathy and resolve, he connects with the crowd, urging unity in their shared struggle to save those affected by the attack. His speech, broadcast live across all news networks, manages to soothe the collective frayed nerves.
Elsewhere, a phone call interrupts Roger's thoughts as a woman scorches him for undermining her crisis management strategy. Roger reveals their shared connection, saying he is with her father, prompting her to hang up abruptly, her identity as Alex revealed. Meanwhile, the Russian official contacts his IT accomplice, Felix, who provides the coordinates of a server farm. With a sinister smile, the Russian begins to shred incriminating documents, leaving a trail of mystery in his wake.
Mrs. Mullen's anxiety is palpable as President Evelyn Mitchell expresses her desire to meet with George. She gently reminds him of his fortunate escape with a clean slate, cautioning him to steer clear of any entanglements. On the second day, George encounters Evelyn, who is assembling a Zero Day Commission with sweeping powers to uncover the attackers, including the authority to make arrests without warrants. Though hesitant to undertake such a role, George finds himself the sole individual she can rely upon.
That evening, the Mullens throw a festive gathering to commemorate Mrs. Mullen's new appointment. Alex harbors suspicions that the government has weaponized the cyber-attack, positioning George as a scapegoat should matters take a turn for the worse. Yet, George's worries escalate when his Mossad contact, Natan, unexpectedly arrives. It transpires that Russia's GRU has been financing a hacking collective in New York, led by Felix, who was recently recruited to establish a colossal server farm in the Bronx.
Elsewhere, Alex and Roger clash, with Alex accusing him of being career-driven, while Roger insists that his actions are solely for George's benefit. Alex warns Roger that her father could be made a scapegoat if he accepts the commission. As George makes his way inside, the haunting strains of 'Who Killed Bambi' by Sex Pistols echo in his mind, sending him into a panic. He hastily instructs Hector to silence the music, though no sound is actually playing; his thoughts are elsewhere. Mrs. Mullen interrupts his reverie, concurring that the commission is a perilous trap but acknowledging that George alone can be entrusted with such immense power.
Later that night, Natan calls, prompting George to jot down notes and secure his journal in a safe. The following morning, George reluctantly accepts the position within the Zero Day Commission, garnering mostly positive reception owing to his unblemished past. That night, another urgent call from Natan sends George scrambling to his safe. His distress alarms Roger and his security team, who eventually break into his study when he fails to respond.
George stands in stunned disbelief as his diary is defaced with repetitive scribbles of "Who killed Bambi?" and "George killed Bambi." Convinced that an intruder has tampered with it, he is about to confront Hector about his safe when he notices a different caretaker, Wayne. Confusion sets in until Mrs. Mullen reveals that Hector retired five years ago, adding another layer of mystery to an already unraveling situation.
