A lengthy road tunnel, connecting Moscow with its suburban areas, stretches beneath a river's depths. It's the end of a July weekend, and traffic is congested: elderly dacha owners with cars packed to the brim with freshly harvested fruits and vegetables, families with infants securely nestled in child seats alongside bored teenagers slumping in the backseats, a smattering of pick-up trucks, vans, and refrigerated lorries, a vigilant police car, an opulent executive-class vehicle with tinted windows, and a tattered taxi blaring raucous music — a typical cross-section of urban diversity.

Midway through the tunnel, where radio signals have long vanished, and mobile phones remain deprived of reception, the steady flow of cars abruptly halts. Initially, people are patient assuming it's an accident up ahead or another road closure for an official motorcade. Yet, the gridlock persists, and after a while, people begin to wonder, leaving their vehicles and striking up conversations. Impatience eventually gets the better of some, and a small group ventures toward the tunnel's exit, embarking on a several-kilometer trek. Their hasty return is accompanied by a panicking crowd and troubling news — there's no way out of the tunnel anymore. An explanation eludes them, rumors spread like wildfire, and panic takes root. The crowd retreats toward the tunnel's entrance, but it's barricaded with imposing railings and concrete gates — the same gates that had sealed the exit, tragically thwarting the escape attempt of a reckless car.

Initially, civility prevails as people await rescue. They exchange jokes, share water, and console each other's children. However, as hours pass without any sign of rescue, mobile signals gone, and isolation sets in — both from the external world and from different segments of the lengthy tunnel — reason gradually dissipates, replaced by mounting paranoia.

A sequence of unforeseeable events transforms law-abiding citizens into a frenzied mob. First, a criminal seizes the opportunity to escape from the police car, killing one officer in the process and acquiring a gun. Next, a group of contract construction workers resort to drastic measures, severing an electricity cable in a futile bid to breach the tunnel's walls. At the same time, an elderly, snake-like official finds access to a covert emergency bunker with a capacity limited to sixty occupants, prompting his assistant to execute a specific protocol to select those who might survive.

Following the massive electrical failure, the trapped individuals, confined beneath ground with limited and rapidly depleting air, begin to act as though they're living through Judgment Day. As tensions escalate, they uncover the existence of a bunker stocked with air, weapons, and essential provisions, but discover that the available space proves insufficient for all.

In less than thirty hours since the lockdown, the gates slowly swing open, welcoming rescuers and ambulances. The true cause of the catastrophe is revealed to be an unprecedented cyber attack targeting the city's infrastructure and key transportation hubs. Emerging from the tunnel, exhausted and shaken, survivors feel as though they've spent an eternity underground, miraculously escaping what can only be described as hell. However, for some, salvation never arrived.