In April 1942, a British submarine surfaced near the coast of Vichy France.

Its mission: to infiltrate agents from the Special Operations Executive (SOE) into the region as spies.

One of the operatives who landed on French soil that night was Eugene Zoltan.

Trained at SOE centres in Britain, his mission was to serve as a wireless operator near the city of Lyon. In that role he would transmit and receive coded messages, as well as helping other agents enter enemy territory and aiding those attempting to escape the Germans or their Vichy subordinates.

But Eugene Zoltan was a cover name, issued to him by the SOE. His real name was Edward Zeff, and he was a 28-year old Brighton-born Jew.

His subsequent story — of betrayal, torture, incarceration and survival — was not fully revealed until 2005, when the UK government released the files on his wartime service.

Now, more than 70 years after he began operating on hostile soil, his sacrifice for his country is due to be honoured with a memorial plaque in the city of his birth.

Captain Zeff will be one of four members of the SOE recognised by the charity Secret WW2 at an unveiling ceremony to take place on November 12.

The organisation is dedicated to educating the public about covert operations, in particular those carried out in Occupied France during the war.

Paul McCue, an SOE historian, is one of the charity’s trustees. He said: “Edward Zeff, little-known until now, has long deserved to have his story told.

“Despite scant knowledge of soldiering and no experience of clandestine warfare, he volunteered to work as a secret agent in enemy-held France in one of the most dangerous roles possible — that of radio operator.”

As described in Mr McCue’s new book, Brighton’s Secret Agents, due to be published next week, Capt Zeff led a heroic — but ultimately tragic — life.

Christine Miller is married to Don Miller, Capt Zeff’s great-nephew. Her research played a key part in telling the story of the Jewish SOE officer.

“My husband’s mother and her sister, Lisa, used to speak of him.

“Lisa had lived in France and it was there that Edward helped her settle, in Paris, in the late 1950s.

“She spent quite a bit of time with him there after the war.

“When he was in one of his dark moods, he would tell her some of the things that had happened to him.

“When his files were released around 10 years ago I went through all of them.”

The documents revealed the full nature of some of those experiences, including incidents which left Capt Zeff with physical and mental damage.

Although he was born in Britain, he had moved to France in the 1920s to join his brother, who had started a tailoring business in Paris. In 1930 he had married a French Jewish woman called Reine Sevilla.

Capt Zeff had returned to Britain when the Germans invaded France in 1940 and, with his fluent French, was soon chosen to be part of the SOE’s French section, leading to his role in infiltrating it in 1942.

During almost a year in Vichy France, he managed to narrowly escape capture on a couple of occasions but the net was closing in.

Aware the Germans were close to apprehending him, the SOE had arranged for Captain Zeff to be spirited out of France via the mountain passes of the Pyrenees. However, he and his group were betrayed by one of their guides.

Arrested, he was initially held in a prison in the south of France but was then transferred to Fresnes prison near Paris.

The Nazis held a number of captured spies at Fresnes during the war, including Peter Churchill and Odette Samson, both famous SOE officers.

Capt Zeff was tortured by the Nazis for information. He was brought to the point of near drowning in an effort to make him talk, as well as being hung from the ceiling and brutally beaten. He was also drugged and subjected to sleep deprivation in efforts to get him to divulge secrets.

Despite this torture, which continued for three months, Capt Zeff revealed no information regarding his work for the SOE.

After the war he was honoured by both the British and French governments, receiving the military MBE and the Croix de Guerre (with Silver Star) for “loyalty, steadfastness and devotion to duty”.

In the meantime, however, after months of refusing to talk, he was deported to Mauthausen, the infamous Nazi concentration camp.

“He was very badly treated there, because not only was he a spy, but he was Jewish as well”, said Mrs Miller. “Lisa told us that he didn’t really speak much about what he had experienced at Mauthausen, although he would often get depressed.

“Psychologically, he was never the same after his experiences.”

Captain Zeff spent the rest of the war mostly in the Mauthausen complex itself, but also in the satellite camp of Melk, where he and other slave labourers were forced to help dig tunnels to hide V2 rocket-making facilities from air attacks.

He managed to survive in Mauthausen by befriending one of the camp Kommandants. According to family lore, this mysterious commander repeatedly managed to get Capt Zeff removed from liquidation lists.

Capt Zeff’s friends in Melk also managed to hide him when he was scheduled to be taken away and killed.

The Nazi authorities may also have made a rare clerical error.

Mrs Miller explained: “When we visited Mauthausen this year, part of the tour was a walk through the memorial.

“My husband was looking through the memorial book and I said he wouldn’t be in there because he survived, he was liberated. But he was in the book as having been executed at Melk.”

Capt Zeff had actually regained his freedom when the Americans liberated the camp in 1945.

He returned to Brighton before moving back to Paris to resume working with his brother, who had also survived the war.

However, the SOE officer’s post-war life was not a happy one. Traumatised by his experiences, he and his wife divorced. He eventually died of cancer in Paris in 1973.

Martin Sugarman, Association of Jewish Ex-Servicemen and Women archivist and historian, was instrumental in the organisation of the plaque.

“Capt Zeff endured the most appalling torture,” he said. “He never gave anything away, and was honoured by both the British and French governments.

“It is fitting that his service is being commemorated in such a fashion in the city of his birth.”