Near the end of his life, Soviet Premier Joseph Stalin had taken to spending almost all of his free time at his dacha in the Moscow suburb of Kuntsevo. Easily depressed when left on his own, he regularly summoned four members of his inner circle to join him there for a movie and a meal.

Stalin’s “comrades-in-arms” at that time included Georgy Malenkov, Stalin’s likely successor and deputy premier; Lavrenti Beria, Stalin’s influential chief of secret police, who was also jockeying for power; Nikita Khrushchev, whom Stalin had summoned to Moscow to balance the power dynamics of Malenkov and Beria; and Nikolai Bulganin, Stalin’s defense minister.

“As soon as he woke up, he would ring us— the four of us—and either invite us to see a film or start some long conversation about a question that could have been resolved in two minutes,” Khrushchev later recounted.

The move was in part for company, in part to keep an eye on them.

In 1953, Stalin was 73. He suffered either a heart attack or a series of strokes in 1945, and his health hadn't been the same since. His paranoia, too, was at an all-time high.

When he had gone in for his regular check-up in 1951, his doctor told him to rest more and work less, words that Stalin did not take well, biographer Roman Brackman wrote in The Secret File of Joseph Stalin: A Hidden Life. “[T]hree decades earlier, plotting to hasten [Premier Vladimir] Lenin’s death and pretending to worry about his health, [Stalin] had insisted that Lenin be kept from his daily duties,” he explained.

The doctor was arrested and charged with working as a spy for British intelligence. But whether Stalin wanted to admit it or not, his health was indeed flagging. When he summoned a Communist Party Congress—the first in over a decade—in 1952, those attending expected it to outline the roadmap of party succession. Instead, New York Times correspondent Harrison Salisbury wrote, “If it had seemed for a short time that the great roles at the party congress were to go to Malenkov and Khruschev, such ideas were quickly dispelled. The great role, the only important one at the congress, was played by Stalin himself.”

Rather than chart a clear course forward, Stalin proceeded to shake up the Kremlin hierarchy, appointing in a host of young, relative unknowns in positions in ways that were “designed to conceal and confuse the lines of succession rather than clarify,” wrote Salisbury.

When it came to members of his inner circle, he especially wanted to remind them they were all disposable. “He liked to repeat to us, you are blind like kittens,” Khrushchev recalled. “Without me the imperialists will throttle you.”

But in the final months of his life, watchers of the Soviet Union could detect something more was going on with Stalin. As rumors swarmed about who held court in his chain of command, in the winter of 1953, Stalin turned his attention toward the Soviet Jews in a campaign that foreshadowed a new wave of purges and party upheaval reminiscent to the Great Terror of the 1930s that had the potential to shake the foundations of the Soviet Union and its leadership.

The situation was such that it’s possible it may have caused his “comrades-in-arms” to risk poisoning Stalin on the night of February 28, 1953.

Late that evening, Stalin summoned Malenkov, Beria, Khruschev and Bulganin like normal to watch a movie. After, they retired to Stalin’s Kuntesvo dacha, where they sat down to a meal, during which Stalin inquired whether confessions had been extracted for a trial he would soon oversee. That winter, Stalin had been waging a witch hunt against Kremlin physicians, many of whom were Jewish, claiming they murdered top Soviet officials in a “doctors' plot. The trial against the Kremlin doctors was to commence within weeks.

According to Khrushchev’s account of the night, they finished around 5 or 6 in the morning. “We said goodbye to Comrade Stalin and departed," he wrote. “I remember that when we were in the entrance hall Stalin came out as usual to see us off. He was in a jocular mood and joked a lot. He waved his index finger or his fist and prodded me in the stomach, calling me Mikola. He always used the Ukrainian form of my name when he was in good spirits. Well, we left in good spirits too, since nothing had happened during the dinner. Those dinners did not always end on a happy note.”

But perhaps all wasn’t so rosy the night of the 28th. “[H]ad some great row finally broken out?” Salisbury asked in his memoir. “Were they prepared to let events move forward and possibly engulf them all? Three of them — Malenkov, Beria and Khrushchev — were as crafty, as skilled, as tough as any figures to be found in Russia. Did those three march down the path to the precipice without making a move to save themselves?”

The next day, a Sunday, Khrushchev says he remained at home, expecting Stalin to call to extend an invitation for that evening. But Stalin did not call him, or anyone else for that matter. He didn’t ring for food, nor had the sensors installed in Stalin’s rooms detected movement.

According to later interviews, those working at the dacha claimed they were too scared to disturb Stalin. But in The Unknown Stalin, historians Zhores Medvedev and Roy Medvedev are suspicious of that narrative: “[I]t would not have been normal for the staff to be afraid of entering Stalin’s room or even to ring him on the house line,” they wrote.

It took until around 10:30 at night for someone to check on Stalin. According to one account, one of the guards, Peter Lozgachev was the one who finally entered Stalin’s quarters, ostensibly to drop off official mail from the Kremlin. Other accounts say it was the longtime maid.

Whoever entered the room found the dictator on the ground in his pajamas, the floor soaked with urine. An empty glass and mineral water were on the table, and it appeared as though Stalin had gotten out of bed to get water, but then had a stroke.

Members of the dacha staff carried him onto the dining room sofa, where they covered him with a rug. While the consensus among those present was to call a doctor, the officers on guard wanted to wait on instructions from the party leadership. Eventually, they got Beria on the phone, who demanded they tell no one of Stalin’s illness.

Beria and Malenkov arrived first at the dacha. According to testimony compiled by Miguel A. Faria in the journal Surgical Neurology International, Lozgachev said that Beria, upon seeing Stalin snoring, asked, “Lozgachev, why are you in such a panic? Can’t you see, Comrade Stalin is sleeping soundly. Don’t disturb him and stop alarming us.”

Even if no one had poisoned Stalin the night before, Simon Sebag Montefiore in Stalin: The Court of the Red Tsar suggested they could have observed the state he was in, and made a decision there to hasten his death. Signs pointed to Beria having fallen out of Stalin's good graces—and thus he potentially stood to gain the most from the leader's death. But Beria could have also believed what he was saying; to an untrained eye, Stalin may very well have appeared to be sleeping. And with the doctors’ plot trial in the offing, no one wanted to have to be the one to call a doctor. “[The inner circle was] so accustomed to his minute control that they could barely function on their own,” Montefiore added.

Intentionally or not, it took until around 7 in the morning for the members to reach a decision to call the Minister of Health to select doctors for an initial look. When the doctors finally arrived, they found Stalin unresponsive, his right arm and leg, paralyzed, and his blood pressure at the alarmingly high rate of 190/110. “They had to examine him, but their hands were too shaky. To make it worse, the dentist took out his dentures, and dropped them by accident,” according to Lozgachev’s testimony. They ordered complete quiet, put leeches behind his ears, a cold compress on his head and recommended he not eat.

Two days after the doctors first saw him, Radio Moscow made the announcement, revealing Stalin had suffered a stroke on Sunday night.

The message said he was receiving suitable medical treatment under the close eye of party leaders, worded in such a way to reassure a public frenzied by the doctors' plot allegations that none of the doctors treating Stalin were in any way connected to the alleged conspiracy. (Ironically, those consulted actually did include several imprisoned Kremlin doctors, according to Joshua Rubenstein in The Last Days of Stalin. One, a pathologist named Aleksandr Myasnikov, said he was mid-interrogation when his captors suddenly started asking for medical advice instead.)

On March 5, Stalin vomited blood and his stomach started hemorrhaging, a detail cut from the final report issued to the Central Committee, until scholars Jonathan Brent and Vladimir Naumov unearthed the detail in 2013.

The long-buried evidence could suggest a cover up. It’s known that on the night of February the 28, Stalin drank "fruit juice" (diluted Georgian wine). Poison, perhaps in the form of the poisonous, tasteless blood thinner warfarin, could have easily been slipped in Stalin’s drink and could have caused his stomach hemorrhaging, Faria writes. But whether that’s the case will likely forever remain a matter of speculation, Brent and Naumov concluded in Stalin's Last Crime: The Plot Against the Jewish Doctors, 1948-1953. That night, Stalin’s iron-fisted 30-year rule over the Soviet Union ended. His death was recorded at 9:50 p.m.

During his three decades in power, the Soviet Premier commanded not just the party leadership, but also the hearts and minds of the Russian public. His personality cult was such that in spite of his reign of terror that caused tens of millions to die, he remained “Uncle Joe,” the "father" of all Russians to his final days.

Upon Stalin’s death, Beria, with his network of spies and contacts, seemed poised to take over. But he fatally underestimated his opponents. As Khrushchev, the outsider, would soon show, the struggle for who would fill the power vacuum left in Stalin's absence was just beginning.