In the icy expanse of the Arctic Ocean, near the edge of the North Pole, a Swedish-led expedition of geologists pushes scientific boundaries with a series of hydrological tests using explosive charges. The duo, Julia and Oskar, work under stark conditions, their snowmobiling trek and careful measurements unfolding against a backdrop of deep blue ice and endless white. When their camp is suddenly swallowed by the shifting ice, the mystery thickens: nearby, the experimental submarine Ataman Yermak has been moving beneath the ice, its mission intertwined with dangerous secrecy. As the crew reports strange activity and then suffers catastrophic damage, the emergency beacon is jettisoned into the cold dark, a beacon that will soon pull two very different fleets toward a shared, perilous fate.
In response to the disaster, the Russian Navy dispatches the deep-diving submarine Zapolyarye, charged with a rescue mission and the grim responsibility of destroying a secret weapon aboard the wrecked Ataman Yermak. Admiral Belousov assigns Captain Second Rank Viktor Voronin to lead the operation, tapping into a long, complicated family history when Viktor’s younger brother, Alexander Voronin, is brought along to share command. Counter Admiral Olshansky accompanies the mission, prepared to step in if the personal stakes threaten professional judgment. The Zapolyarye carries a deep submergence rescue vehicle that could prove pivotal if crews are trapped or wounded. Viktor receives a father’s dive watch as a symbolic reminder of lineage and duty, a small yet meaningful token amid the enormous pressures of command.
As Zapolyarye closes in on the beacon and the stricken vessel, the crew’s sonar picks up a pod of whales behaving oddly, a rare and unsettling sign in the open sea. An otherworldly silhouette glides through the sonar, and Olshansky urges a lethal response with torpedoes. Voronin, however, chooses to hide among the sea ice, narrowly avoiding a confrontation that could jeopardize the mission. The encounter leaves the ship battered but intact, and the crew narrowly rescues Julia and Oskar from the frigid waters. The different instincts within the command structure come into sharper relief: Olshansky wants to turn back toward Murmansk, while Voronin presses on, intent on continuing the search.
The pursuit intensifies as the kraken-like anomaly—an immense predator of the deep—stalks the Zapolyarye, soon dragging the vessel toward a Norwegian oil rig that is swallowed by the creature. Olshansky deems Voronin’s leadership to be a dangerous risk and relieves him, marking what he calls the third mistake in a run of tense judgments. Voronin refuses to back down, reasserts control, and orders a crash dive, cutting nonessential systems to endure the pressure. Despite grievous damage, the ship presses deeper, and the decision to return to base is weighed against the possibility of locating the Ataman Yermak and the missing crew.
On the surface, Julia returns with a crucial revelation: the researchers’ work may have disturbed the Kraken, a colossal creature guarding its lair far below, potentially in a region known as the Nansen Basin. A faint, metallic howling echoes through the sonar as Voronin considers a dangerous continuation toward the abyss. The plan shifts toward a coordinated search that will rely on a deep-submergence rescue vehicle (DSRV) to locate the lost submarine. Amid a graveyard of ships, the Ataman Yermak is found; its stern is crushed while the bow remains intact. Into the escape trunk, some of the crew are evacuated, including Viktor’s brother Alexander, but Viktor, Alexander, and several others stay aboard to disable the Ataman Yermak’s experimental weapon.
Koshkin, piloting the DSRV, maintains a beacon on the hull even as the mission’s peril grows. The beacon’s reactivation rekindles the Kraken’s pursuit, forcing Zapolyarye into a perilous surface situation. The DSRV finally reaches the enigmatic wreck, the Kraken pressing close as the two vessels fight for control in the depths. In a desperate, final move, Viktor and Alexander decide to activate the weapon—an enormous energy beam meant to eradicate the monstrous threat. The weapon’s self-destruct sequence follows, but the crew makes a harrowing escape to the DSRV, the bow of the Ataman Yermak breaking away and plummeting into the abyss.
Surface tension remains as Zapolyarye rises, its crew led by Olshansky, who waits for the DSRV to surface with the two brothers triumphant in the end. Viktor offers the recovered dive watch as proof of his earned responsibility, and Alexander confirms the achievement. The submarine returns to Kola Bay, the two brothers standing together atop the conning tower, the balance of duty and family bonds having carried them through an extraordinary ordeal beneath the ice.
