Next week the Southwark Playhouse in London will host what will be only the second production in Britain of Ernest Hemingway’s 1937 play, The Fifth Column (the first, produced by Michael Powell, toured in early 1944). Hemingway wrote the play while in Madrid covering the Spanish civil war for the North American Newspaper Alliance. Although the main fighting was by then in the north, Madrid was still subjected to daily artillery bombardment and aerial bombing. Virtually surrounded by four columns of Francoist troops, the city was plagued by a fifth column of snipers and saboteurs. Although not a great play, it is a fascinating one for what it tells us about Hemingway himself.

The plot is relatively simple and revolves almost exclusively around Philip Rawlings, an American counter-espionage agent of the Comintern who describes himself as a “sort of a second-rate cop pretending to be a third-rate newspaperman”. The central theme is the conflict between Rawling’s duty in the merciless fight against the Fifth Column and his desire for Dorothy Bridges, a tall, glamorous blonde with vague connections to Cosmospolitan magazine. The weary, cynical, yet romantic Rawlings is a projection of Hemingway himself: he has “big shoulders and a walk like a gorilla”, likes raw onions, corned beef, neat whisky and Chopin records, and drinks at Chicote’s bar. When he lists where he might go with Dorothy in France, Kenya and Cuba, they are all places that Hemingway had visited with his wife Pauline Pfeiffer.

The action takes place either in the Hotel Florida, a hotel with enough bed‑hopping and intrigue to emulate a French farce, or in the dour headquarters of the security services. The Florida is where Hemingway stayed in Madrid and where he fell in love with journalist Martha Gellhorn. Rawlings’s room is a replica of Hemingway’s, complete with the cupboards full of tinned food and the portable gramophone. Written during the first year of their affair, the cruel portrait of Bridges, “a bored Vassar bitch”, seems to reflect Hemingway’s views on women in general and Gellhorn (who went to the equally elitist Bryn Mawr) in particular. Bridges is presented as a vacuous rich woman, who survives on tinned foie gras and jugged hare while longing to return to her pampered background of Paris and the Riviera. Rawlings says that he would “like to marry her because she’s got the longest, smoothest, straightest legs in the world”, something he used to say about Gellhorn, but he also calls her “lazy, and spoiled, and rather stupid and on the make”. Like Gellhorn, Bridges takes advantage of black-market exchange rates to buy a silver fox fur coat on the cheap.

When Dorothy asks him: ‘Don’t you want to have a long, happy, quiet life at some place like Saint-Tropez … and have long walks, and go swimming and have children and be happy and everything?’, Rawlings is tempted but feels guilty when he counterpoints his relationship with Dorothy against his secret work. A member of the Fifth Column escapes while the sentries sleep. While Rawlings is in bed with Bridges, a young international brigader is shot by a Fifth Column assassin who thought he was killing Rawlings. With hardened anti-Nazi German comrade Max, Rawlings goes behind the lines and captures a rightwing politician who, under interrogation, reveals all he knows about the Fifth Column. Max, who has been badly tortured and disfigured by the Gestapo, perceives Rawlings’s dilemma, torn between his yearning for a pleasant life with Dorothy and the needs of the war. To defend the Republic from the Fifth Column, Rawlings has to accept the necessary murders and brutal interrogation methods.

The grim context of the play is lightened by comic moments involving a prostitute and a permanently hungry hotel manager, with the humour generated by the pidgin English with which Hemingway patronisingly renders their Spanish. If that tells us something about the man, how much more can we learn from the character described as the “thin-lipped security chief”? It has been widely assumed that “Antonio” is based on Pepe Quintanilla, the brother of the famous Republican artist Luis Quintanilla, one of Hemingway’s oldest and closest friends in Spain. In fact, Antonio says more about Hemingway’s vicarious pleasure in the murky side of the interrogations and tortures involved in the struggle against the Fifth Column. In her colourful account The Starched Blue Sky of Spain, the novelist Josephine Herbst, one of the American writers holed up in the Hotel Florida, claimed that Hemingway told her that Pepe was the “head of the department of justice” (although this is contradicted by her own unpublished diaries of the time). John Dos Passos, in his novel Century’s Ebb and in his book Journeys Between Wars, portrays Pepe as “the then chief of the Republican counter-espionage service”. Antonio has been described elsewhere in books on Hemingway as a “dramatic recreation of the thin-lipped executioner of Madrid, Pepe Quintanilla” and the “chief of Madrid’s secret police”.

This distortion of the role of Pepe Quintanilla has contributed to torrid accounts of the Republican secret service implementing mindless Stalinist-style repression, which was certainly not Hemingway’s intention since he approved wholeheartedly of the fight against the Fifth Column. The creation of Antonio came from Hemingway’s own peripheral involvement, along with Dos Passos and Herbst in the notorious case of José Robles, a friend of Dos Passos who was arrested and later executed by the Republican security services for his alleged links with the Francoist fifth column. The picture of Pepe as a monster who typified the Republican security services derives from the accounts by Herbst and Virginia Cowles of a lunch on 28 April 1937. Cowles noticed a “fastidious-looking man dressed from head to toe in dove grey. He had the high forehead and long fingers of the intellectual and wore horn-rimmed spectacles which added to his thoughtful appearance.” Noticing her interest, Hemingway could not resist showing off, saying dramatically, “That is the chief executioner of Madrid”, and inviting Pepe to join them. Pepe then gave an exaggerated account of the fight against the Fifth Column, perhaps relishing his capacity to startle the two women. In fact, his real job was as the administrative assistant to the head of Republican counterespionage – David Vázquez Baldominos, head of the special brigades, one of which arrested Robles. It is extremely doubtful that Pepe was personally involved in executions, although he would have had access to important information about them.

As Pepe regaled them with stories of the first days of the war, shells began to rain down and he coolly counted the explosions as he poured wine. By the time he got to 10, the air was thick with fear. When Hemingway pressed a now drunk Pepe to talk about the struggle against the Fifth Column, the atmosphere grew even thicker. Hemingway beamed and the women squirmed as Pepe told them about a Fifth Columnist who soiled himself “huddled in a corner” then “had to be carried out and shot like a dog”. Pepe ordered brandy and flirted outrageously with Cowles who later remembered only what she took to be sadism in his “bright marble-brown eyes”. When they left the restaurant, Hemingway said to her, “Now remember, he’s mine.” He thus gave the game away, revealing that he saw Pepe both as a prize with which to show off his own privileged status, a unique source and also a character in a play.

• The Fifth Column runs at the Southwark Playhouse, London SE1 from 24 March to 16 April.