“When he was young, Coba was very fond of hunting, but not with a rifle, he preferred traps,” wrote Leon Trotsky in his essay in 1939. And who could know it better than Trotsky, for whom Coba (a.k.a. Joseph Stalin), his former comrade-in-arms and a close associate at the Politburo, was setting traps all over the world, which Trotsky, a weathered conspirator, kept eluding. Until, finally, the trap’s jaws clapped over their victim.

Exactly 50 years ago, on a hot August day in 1940, a young Spaniard, Ramon Mercader, walked freely into Trotsky’s heavily fortified house in Coyoacán, a suburb of Mexico City, said hello to the guards, declined politely the tea offered to him by Trotsky’s unsuspecting wife Natalia, then, on the pretext of discussing with Trotsky his article about the Fourth International, accompanied the old man to his study, and there brutally crushed Trotsky’s skull with an ice pick. That blow ended what had begun peacefully, almost idyllically three years prior—Trotsky’s final refuge in Mexico.

After Coba expelled him from Soviet Russia in 1929 (one can well imagine how madly he later cursed himself for making such a stupid mistake, allowing “this Judas” to leave), Trotsky attempted to settle in Turkey, but had to flee for France, which he, in turn, had to flee for Norway, where he couldn’t remain either, because Coba threatened the Norwegian government with a boycott of Norwegian herring for harboring him.

The situation was getting quite tense—no country was willing to give refuge to the prophet of world revolution. And then, a blessing, a salvation from totally unexpected quarters. Diego Rivera, a muralist painter and the most famous artist in Mexico (who also happened to be a Trotskyite) requested political asylum for Trotsky and his wife Natalia from Mexican President Cárdenas. And Cárdenas consented.

The Trotskys settled at the Riveras’ large, azure-painted residence, their so-called “Blue House” in Coyoacán. Although Diego loved to repeat that he had “no home, only the Communist Party,” he and his wife, the artist Frida Kahlo, lived quite comfortably. The Blue House, one of several houses they had, was filled with pre-Colombian Mexican art and works of Picasso, Miro, and Duchamp. “We are on a different planet!” excitedly wrote Natalia Trotsky, unaccustomed to this combination of wealth and Bohemia.

Diego was a vigilant and sensitive host. The Blue House’s windows facing the street were bricked up; he even bought the large neighboring parcel of land and surrounded the entire property with a stone wall that was guarded around the clock by an international group of Trotskyites. Frida’s father, an old provincial photographer from Hungary, couldn’t quite understand who all these people were, who Trotsky was, and what the commotion was about, and when she explained it to him, said: “If you respect this man, tell him to stay away from politics—it’s a heap of manure!”

In the Blue House’s cozy kitchen, the hosts and the guests would eat together, often staying up late, discussing art and the future of mankind. Trotsky would recall his plans for Soviet military strategy—”the road to Paris and London runs through the towns of Afghanistan; from a base in the Urals, via Afghanistan, the red cavalry should move into India and set off an Asian revolution . . .”; he would talk about art—”in the future communist society art will dissolve into life; there will be no dancers, for instance, since everyone will move harmoniously . . . “; or make pronouncements on politics—”the tribunal of History will condemn Cain-Stalin . . . !” Somehow, he and Stalin, both militant atheists, liked to hud biblical insults at each other.

Soon after his arrival in Mexico, Trotsky requested that a commission be established to investigate the allegations brought against him at the Moscow show trials. And so it was. In the presence of about fifty spectators, mostly American and Mexican reporters, the seven-member International Commission, chaired by John Dewey, held its sessions in the Blue House’s spacious living room. Because of concern for G.P.U. sabotage, the house was surrounded by piles of sandbags, and everyone was searched for weapons before being admitted inside.

For Diego and Frida this was a dream come true. A “happening,” a piece of tense theater and a dangerous political event—all entangled in one! They both would come to the solemn commission sessions dressed extravagantly—she in long, native Indian outfits, multicolored shawls and exotic earrings, and he wearing a huge, fit-for-a-circus sombrero adorned with a peacock feather.

After a week of daily hearings, the Dewey Commission completely absolved Trotsky of all charges brought against him in Moscow.

The kitchen discussions continued. To communicate, they resorted mainly to French. Diego also knew some Russian (his first wife was Russian painter Angelina Belova), while Frida loved to switch into English, which Natalia Trotsky didn’t know.

Diego was excited to have at his dinner table, in the flesh, the man whom he used to depict on his frescoes next to Lenin. And the sickly and wanton twenty-nine-year-old Frida (who was much younger than her husband) was flattered by the increasingly tender attention paid to her by the former legendary commander of the Red Army. She flirted with him and even gave him a nickname, el Piochito—the little goat.

And Trotsky was, apparently, taken by her. As one of his aides recalled, “He would write her a [love] letter and slip it into a book and then would give the book to her, often in the presence of Natalia and Diego, insisting that she read it.”

And, of course, she would.

Soon, to the great dismay of Trotsky’s bodyguards, who were concerned for his safety, el Piochito and Frida were secretly seeing each other at the house of Frida’s sister, Christine.

On Trotsky’s birthday, November 7, 1937, which also happened to be the anniversary of the October Revolution, Frida presented him with her self-portrait. In a long flowery dress, a red carnation stuck in her pitch-black hair, she was staring intently from the canvas that bore the description: “To Leon Trotsky, I dedicate this with love.”

The good thing was that neither Diego nor Natalia suspected anything—Diego, because he himself was involved in several simultaneous love affairs, and Natalia because she was totally absorbed in her husband’s building of the Fourth International (of which Diego was a distinguished member). And, of course, it helped that el Piochito was an old conspirator, and that Frida could lie breezily.

But the bad thing was that Frida’s mood and passion were rather changeable, to say the-least. After a few months, she (who according to the current Fodor’s Mexico “was addicted to alcohol and drugs and had affairs with . . . several women”) got bored with Trotsky. Despite old Piochito’s desperate pleadings, she dropped him.

Trotsky’s relationship with Diego also started falling apart. Diego was becoming more and more irritated with Trotsky’s stubbornness, his grim dogmatism, his (as Rivera perceived it) lack of humor. And Trotsky was getting more and more annoyed with Diego’s anarchist tendencies, his “lack of principles,” his Bohemian attitude toward party matters, his weird jokes.

Trotsky was particularly upset when, at the time his one son was poisoned by the G.P.U. in Paris, and another son arrested and shot in Moscow, Rivera presented him with a red skull made from sugar on whose forehead in big white letters was written—STALIN. The moment Rivera left, the angry Trotsky ordered his aide to break and throw away this “gift.”

Soon thereafter, it became known that Diego decided to leave the Fourth International. This Trotsky could not tolerate. Through the Mexican press, he announced that he “no longer shared moral proletarian solidarity with Diego Rivera and thus could not continue living in his house.”

In April of 1939, after spending two years and three months at the Riveras’, the Trotskys, their aides, and bodyguards moved out and settled in Vienna Street, also in Coyoacán.

For the next year there was no communication between the two couples, although they lived less than a mile from each other. Meanwhile, the G.P.U. grip around Trotsky tightened. A plot to assassinate him, headed by the communist painter David Siqueiros, was organized. According to Nicholas Mosley, “The conspirators gathered in a studio-room on Cuba Street in the city on the night of 23rd-24th May [1940]. They were mostly artists, ex-soldiers, mineworkers, the unemployed. There was with them an agent of the G.P.U. known as Felipe. They had acquired police uniforms; they dressed up. The second-in-command of the raid, a painter called Pujol, wore the uniform of an army lieutenant: Siqueiros himself wore the uniform of a major, with dark glasses and a false moustache. They carried ropes, ropeladders, rubber gloves, incendiary bombs, a rotary saw, several revolvers, and at least two machine guns . . . the moustache Siqueiros wore, was a ‘Hitler’ moustache [and] instead of an officer’s hat he had a [First World War] ‘Kaiser’ helmet.” It was a combination of “murderous solemnity and farce.”

Trotsky, however, was not amused. In his letter to Mexican President Cárdenas, written immediately afterwards, he described what had happened. “A gang of twenty assassins attacked my house at night, tied up the guards, broke into my study, threw fire bombs into the house and into the yard, wounded my grandson, and kidnapped one of my aides.” For some reason, he chose not to mention that he and Natalia survived only by chance, rolling out of their bed and hiding behind it when their bedroom was hastily machine-gunned from the doorway.

A few days later, the corpse of Trotsky’s kidnapped aide was found buried in the basement of the house of Siqueiros’s relatives. Since the quarrel with Rivera was widely known, Diego (who was not involved) became a suspect. He escaped arrest thanks only to his mistress, who drove him away in her truck under a pile of oil paintings. Shortly thereafter, he left Mexico for San Francisco. And thus he wasn’t in the country when the second, successful attempt on Trotsky’s life was carried out three months later.

Though the house on Vienna Street was turned practically into a fortress, with a steel door and watch towers, and was guarded round the clock by the Mexican police and by Trotsky’s bodyguards, the assassin had no trouble getting in, since he was a boyfriend (alas, G.P.U. planted) of Trotsky’s devoted secretary Sylvia Ageloff.

After he hit Trotsky with an ice pick, which went two-and-three-quarter inches into his skull, “Trotsky leaped to his feet . . . and came towards him, sweeping the objects off the table and hurling them at him—the books, the dictating machine, the ink-well, the paper-knife—he grappled with Mercader, tore the ice-pick from him, got hold of his finger and bit it.” Natalia and the guards who rushed into the room saw Trotsky bleeding profusely, but on his feet, and Mercader, in shock, screaming: “They made me do it! They’ve got my mother!” Trotsky died the following evening.

After his death the Riveras made an amazing transformation. Diego turned into a Stalinist. And he begged to be admitted into the paranoidly Stalinist Mexican Communist Party. To get party favors, he even claimed that he was involved in the Trotsky assassination, which was not true.

The change with Frida was no less dramatic. She started hating Trotsky. And the more she hated him, the more passionate, the more obsessive grew her love for Stalin. His photograph was tacked permanently over her bed. And lying in this bed, afflicted with syphilis and a bone disease, barely able to hold a brush, she would devotedly paint Stalin’s portrait.

Now, in the Blue House, there is not even a trace of Trotsky. And in the bedroom where he and Natalia spent more than two years, stands the bust of Coba.