Patricia Owens, the Canadian-born actress best known for her leading role in the classic 1958 film "The Fly," lived in fear that her glittering Hollywood life would come to an end if anyone knew her secret.

It was the 1950s, and the infamous Hollywood blacklist was terrorizing anyone in the entertainment industry whose political beliefs didn't bleed red, white and blue.

But while Sen. Joseph McCarthy was chasing down suspected Communists, Owens was not worried about any Marxist leanings ending her career.

Instead, the Golden, B.C.-born actress was worried because her father, Arthur Owens, was believed to be a Nazi spy. Which he was. And wasn't. It's rather complicated.

Arthur Owens was a British war hero who saved thousands of Allied lives, according to a new book, "Snow -- The Double Life of a World War II Spy," by espionage writer Nigel West and documentary filmmaker Madoc Roberts.

Using thousands of declassified documents from British intelligence services, the writers weave a fascinating tale of a complicated man pivotal to world history, but one whose motivations still lie in the shadows.

Arthur Owens was a Welsh nationalist who had little love for the Crown. As Europe hurtled toward the Second World War, Owens -- code name Johnny O'Brien -- was delivering information to Adolf Hitler's Germany on Britain's military activities.

But some 20 years before James Bond made such spy lingo ubiquitous, Owen was actually Britain's first double agent for MI5 (the country's famed counter-intelligence agency).

"He was the first double agent MI5 had before the war and was absolutely pivotal to the double-cross system which saved thousands of lives," Roberts said in a telephone interview from Cardiff, Wales.

Prior to 1939, MI5 had long been criticized for its policy of immediately arresting and sending all enemy agents to trial, and possibly the firing squad. Many of those captured spies would offer to switch home teams, but the U.K. was having no part of it.

That policy changed when Arthur Owens -- MI5 code name "Snow" -- offered to turn on his German masters and instead, spy for the British.

A businessman who was dealing with both the British and German navies, he initially was recruited by Britain's other intelligence service, MI6, in the mid-1930s before the Germans got hold of him.

"The Germans thought they had their master spy," Roberts said.

But Owens, the most important member of MI5's top secret XX unit (the X's standing for "double cross"), would help deliver dozens of German spies to the British before the war was over.

Many of those spies were be given the same offer as Owens, and would spend the rest of the war delivering information to the British and misinformation to the Germans.

Owens' work helped the Allies break the Germans' Enigma machine -- the country's so-called unbreakable encryption code system. The double-crossing agents also fooled Hitler into thinking the D-Day invasion would take place in Calais, France -- not at Normandy.

But Owens, ever the Welsh nationalist, was never fully trusted by the British and certainly never reaped glory for his pivotal role in the war effort. The British finally sent him to prison in 1941 because they were unsure where his loyalties really stood. He stayed there for the rest of the war, turning German spies over to the British from behind bars.

He went to prison shortly after a German intelligence officer accused him of being a British double agent during a meeting in Lisbon, Portugal. However, for whatever reason, most likely a power play within the German intelligence community by those who didn't support Hitler, this information was never relayed up the chain of command. Owens did tell his British superiors his cover was blown. That was the final straw for them -- what game was he playing? They sent him to Dartmoor Prison.

Owens disappeared after the war, ending up in Ireland under a pseudonym -- Arthur Graham White (remember his code name was Snow). His name was sullied. German war records, all made public, had declared him one of their own. The British intelligence records were declared state secrets and would not be made publicly known until at least the 1970s.

Owens' name had already been blackened locally. He had a binary character -- he was at once an incredibly clever spy, but also a gregarious, boastful man at the pub who could down booze with the best of them. Everyone knew there was more to him than met the eye.

"Even when he was a spy, everyone knew he was a spy," Roberts said. "No one was really quite sure what side he was on."

A double agent (or even a triple agent) has no shortage of possible enemies. It was time to disappear after the war. And he did.

"There was also talk at the time about hanging the double agents," Roberts said. "So, maybe that was one of the reasons he ran away."

The Canadian connection

Owens lived in Canada for 13 years, with his company, Owens Battery Company, holding an office at Toronto's Yonge and King Streets in the early 1930s.

He came to Canada in 1921 with his wife Jessie and his son, Robert. He worked as a teacher and an engineer and also took up Canadian citizenship.

Patricia Owens was born in 1925 in Golden, B.C., then moved with her mother and father to England when she was eight. At a young age, her father would take her on a trip to Germany.

Her mother and father split at the start of the Second World War. Arthur Owens was a well-known philanderer (it's believed the Germans bribed him with women) and he left his family and ran off with a mistress.

He took a second wife eventually, and they had a boy, Graham White.

It was through White that Roberts was able to learn of the connection to Patricia Owens.

Roberts knew the double agent "Snow" had a daughter named Pat, because of the released MI5 files, but had thought that his daughter could not be the Hollywood actress. It would be unbelievable.

But Graham White told Roberts that his mother took him to "The Fly" and said that Patricia Owens was his sister.

"When he told me that was actually the case, it was a massive surprise," Roberts said.

Graham White had a very different opinion of his dad than his half-siblings.

Patricia Owens' mother had gone to the British authorities after her husband left her to tell them that Arthur Owens was a Nazi spy.

"The children knew their mother was accusing their father of being a German spy," Roberts said.

Needless to say, the actress did not grow up with much of a positive image of her father. She moved to the United States in 1956, and soon starred in Marlon Brando's "Sayonara," in which she played his scorned fiancée.

However, it was the 1958 sci-fi classic "The Fly" with Vincent Price that she would be best remembered for.

It would not be until the 1970s, well after her career had fizzled out, that she would learn her father had been a double agent.

"She was horrified," Roberts said, as even the books describing the double-cross system Owens helped set up "took a very grim view of him."

"The fact he was a double agent wasn't very well known."

Many of the books about Arthur Owens were based on German sources, which were, of course, based on the false information placed by MI5.

She came to look for her father in the 1980s, but all she would find was an unmarked grave in Ireland. Arthur Owens, or at least Arthur Graham White, had died in 1957 -- during the height of her fame.

However, his son, Graham White, has gone on the record saying he thinks it's possible his father faked his death and disappeared once more.

"I can't say I saw his body in a coffin and my mother didn't go to the funeral, which made me curious. I wonder if he did die or engineered his departure," he told the Irish Independent.

"There may be an empty coffin lying six feet under in Wexford."

White said he wants to put a grave marker on his father's burial site, but he's not sure what the tombstone would say.

Roberts is telling the story in hopes of sparking a documentary on the extraordinary life of Owens.

"He's never been completely redeemed, people are still doubtful about what his motives were," he said.

"You never know with these spies."

Follow Josh Visser on Twitter

Josh.Visser@bellmedia.ca