If I put some of these real spy operations into a thriller, there’s a good chance an editor would tell me to tone them down.

A dead man carrying fake invasion plans.

A fake Hollywood movie created to smuggle Americans out of Iran.

A CIA ship secretly built to steal a Soviet submarine from three miles beneath the Pacific.

A tunnel dug underneath communist-controlled Berlin so intelligence officers could tap Soviet communications.

And yes, at one point the CIA actually tried turning a cat into a listening device.

As a thriller writer, I spend a lot of time asking myself the same question:

Would readers actually believe this?

History has taught me that sometimes the better question is:

Has someone already done something crazier?

Because intelligence history is filled with operations involving deception, engineering, nerve, improvisation, and ideas so ridiculous they probably would have been rejected from a writers’ room.

Here are seven of my favorites.

1. Operation Mincemeat: The Spy Who Was Already Dead

Imagine pitching this plan during World War II:

Find a dead body. Dress him as a British military officer. Give him an entire fake identity. Chain a briefcase containing fabricated classified documents to him. Then release the body near Spain and hope those documents eventually reach German intelligence.

That was essentially Operation Mincemeat.

In 1943, the Allies were preparing to invade Sicily. The problem was obvious: Sicily was such a logical target that German forces were preparing for exactly that possibility. British intelligence needed Germany looking somewhere else. So they created Major William Martin, an officer who didn’t actually exist.

The deception went far beyond simply putting forged documents in a briefcase. Intelligence officers constructed pieces of an ordinary life around him—the kind of seemingly insignificant details that make a cover story believable.

Then the body carrying documents suggesting Allied plans elsewhere in the Mediterranean was released off the coast of Spain. The information eventually reached German intelligence.

The deception worked.

German attention and resources were shifted partly toward Greece and other possible targets while the Allies prepared for Sicily. The entire operation succeeded because intelligence officers understood something every good thriller writer eventually learns:

The big lie isn’t always what convinces someone.

It’s the tiny details surrounding it.

Why this belongs in a thriller

There are elaborate technological operations on this list, but Mincemeat remains one of my favorites because its primary weapon was a story.

The British didn’t just forge documents.

They created a character.

They gave him a history, relationships, possessions, and enough mundane evidence of a life that someone examining him would hopefully reach the conclusion intelligence officers wanted.

That’s espionage through storytelling.

And as an author, I have to respect it.

2. Project AZORIAN: The CIA Tried to Steal a Soviet Submarine

In 1968, Soviet submarine K-129 disappeared in the Pacific.

The Soviets searched for it.

They couldn’t find it.

The United States did.

The submarine was sitting roughly three miles beneath the surface, and American intelligence officials realized that recovering it could potentially provide extraordinary information about Soviet weapons and technology.

There was only one small problem.

You couldn’t exactly sail into the Pacific with a gigantic crane, steal a Soviet submarine, and expect nobody to ask questions. So the CIA created a cover story worthy of a Bond movie.

With billionaire Howard Hughes providing credibility, the United States built the Hughes Glomar Explorer, supposedly designed for deep-sea mining.

Its actual mission was considerably more ambitious.

The ship contained an enormous mechanical capture system designed to reach the ocean floor, grab part of the submarine and pull it into the ship through a concealed opening.

And they attempted this while Soviet vessels were nearby.

The operation partially succeeded. During the lift, part of the submarine broke away and fell back toward the ocean floor, but the remaining section was recovered.

CIA would later describe Project AZORIAN as one of the great intelligence achievements of the Cold War.

Why this belongs in a thriller

Forget the espionage part for a second.

The engineering alone sounds insane.

The CIA essentially needed to invent technology capable of lifting a massive object from miles beneath the ocean while simultaneously convincing the world that nothing unusual was happening.

That’s what makes operations like AZORIAN fascinating to me.

The best espionage isn’t always someone sneaking through a building with a suppressed pistol.

Sometimes it’s hundreds of people constructing something enormous while protecting the tiny secret hidden at its center.

3. Operation GOLD: They Dug a Tunnel Into East Berlin

During the Cold War, Soviet communications presented Western intelligence agencies with an obvious problem.

They wanted to hear them.

So the CIA and Britain’s Secret Intelligence Service came up with a remarkably straightforward solution:

Dig underneath East Berlin and tap the cables.

The resulting Berlin Tunnel, known to the CIA as Operation GOLD, stretched approximately 1,476 feet from the American sector into East Berlin.

Construction began in 1954 under the cover of a U.S. Air Force radar installation and warehouse.

Thousands of tons of soil had to disappear without attracting attention.

Once completed, British technicians tapped Soviet communication lines and intelligence began pouring in.

According to CIA’s historical account, the operation eventually produced tens of thousands of reels of recordings and hundreds of thousands of transcribed conversations.

There’s an even better twist.

The Soviets already knew about it.

George Blake, a Soviet mole inside British intelligence, had informed the KGB of the operation during its planning stages. But immediately exposing the tunnel could have compromised Blake, so Soviet intelligence allowed it to continue before staging its eventual “discovery” in 1956.

Even more remarkably, later analysis concluded the Soviets had not simply filled the compromised lines with fake information.

The intelligence collected through the tunnel was real.

Why this belongs in a thriller

This is the kind of plot twist readers accuse authors of inventing purely for dramatic effect.

The West secretly builds a tunnel to spy on the Soviets.

The Soviets secretly know about the secret tunnel.

But they can’t expose the secret tunnel because doing so might expose their secret mole.

So everybody keeps playing the game. That’s espionage in its purest form. Everyone knows something. Nobody knows exactly what everyone else knows.

And revealing the truth can sometimes be more dangerous than protecting the lie.

4. Operation Gunnerside: Nine Men Against Hitler’s Heavy Water

Not every incredible intelligence operation involved elaborate deception.

Sometimes the plan was terrifyingly simple:

Get inside.

Destroy the target.

Get out.

During World War II, Allied leaders became deeply concerned about German access to heavy water produced at the Vemork facility in occupied Norway. Heavy water had potential applications in nuclear research, making the plant an important target.

An earlier attempt to attack the facility ended disastrously.

Then came Operation Gunnerside.

In February 1943, a small group of Norwegian commandos crossed brutal winter terrain and infiltrated the heavily guarded facility.

Instead of taking the obvious guarded route, they traversed a steep ravine and approached through a less protected area.

They entered the plant.

Placed explosives.

Destroyed critical heavy-water production equipment and hundreds of kilograms of heavy water.

Then escaped.

The sabotage team suffered no casualties during the raid.

Some of the men then escaped hundreds of kilometers across Norway toward Sweden on skis while German forces searched for them.

Why this belongs in a thriller

Operations like Gunnerside are a reminder that real covert missions rarely have the safety net fiction sometimes gives its heroes.

There was no guarantee of extraction.

No certainty that the intelligence was perfect.

No convenient rescue waiting if things went wrong.

Just preparation, improvisation and the understanding that failure could have consequences far beyond the men carrying the explosives.

That’s the kind of pressure I find far more interesting than an invincible super-spy.

5. Operation Ivy Bells: America Tapped an Underwater Soviet Phone Line

During the Cold War, the United States discovered that the Soviet Union had an underwater communications cable running through the Sea of Okhotsk.

The cable carried sensitive Soviet naval communications.

There was just one issue.

It was deep inside an area the Soviets considered protected territory.

American intelligence wanted to listen anyway.

Beginning in the 1970s, the specially modified submarine USS Halibut secretly entered the area while divers searched the seafloor for the cable.

Eventually they found it.

Instead of cutting into the cable—which could reveal the intrusion—a listening device was designed to capture communications without physically piercing it.

American submarines could then return and retrieve the recordings.

The gamble paid off spectacularly because the Soviets apparently considered the physical cable secure enough that some sensitive communications passing through it weren’t encrypted.

For years, American intelligence had access to information traveling through a communication system the Soviets believed was protected.

The operation eventually ended after former NSA employee Ronald Pelton betrayed the program to the Soviet Union.

Why this belongs in a thriller

There’s something almost unnerving about Ivy Bells.

No explosions.

No car chases.

No shootouts.

Just men operating beneath freezing water inside Soviet-controlled territory, attaching a listening device to a cable that was never supposed to be found.

And if they were discovered?

There probably wasn’t going to be a press conference explaining the misunderstanding.

6. Acoustic Kitty: Yes, the CIA Tried to Create a Spy Cat

This one sounds like somebody lost a bet.

During the 1960s, the CIA explored whether an ordinary cat could be transformed into a mobile surveillance platform.

The logic wasn’t completely ridiculous.

People notice strangers standing nearby.

They usually don’t notice a cat.

So if a cat could casually wander near a sensitive conversation, perhaps intelligence officers could listen without placing a human operative at risk.

A microphone was placed in the cat’s ear, a small transmitter beneath its skin, and an antenna concealed within its fur.

Technically, the surveillance equipment worked.

There was another problem.

They had attached it to a cat.

And cats are not particularly interested in national security objectives.

During testing, controlling where the animal went proved extremely difficult. CIA eventually concluded that the approach wasn’t practical for real intelligence operations.

The project was abandoned.

Why this belongs in a thriller

Sometimes intelligence history teaches us about courage.

Sometimes deception.

Sometimes technological ingenuity.

And sometimes it teaches us that no matter how large your budget is, you still can’t tell a cat what to do.

7. Argo: The CIA Created a Fake Hollywood Movie to Rescue Six Americans

This operation became famous through the movie Argo, but strip away Hollywood’s dramatization and the real premise remains astonishing.

After militants seized the U.S. Embassy in Tehran in November 1979, six American diplomats escaped capture and eventually took refuge with Canadian diplomats.

Getting them out of Iran presented a serious problem.

CIA officer Tony Mendez, a specialist in disguise and exfiltration, developed an extraordinary cover story.

The Americans would become members of a Canadian film crew scouting locations for a science-fiction movie.

But simply handing six people fake identities wasn’t enough.

The movie had to exist.

So the CIA helped create Studio Six Productions in Hollywood.

The fake production had an office.

A screenplay.

Advertisements appeared in the entertainment press.

The project even had a name:

Argo.

Mendez traveled to Tehran, helped prepare the six diplomats for their new identities, and on January 28, 1980, the group passed through the airport and escaped Iran.

Six Americans walked out of a hostile environment protected by one of the strangest cover stories intelligence officers had ever created.

Why this belongs in a thriller

The genius of Argo wasn’t simply inventing a lie.

It was understanding that the lie had to survive investigation.

If someone called Hollywood, there needed to be a production company.

If someone searched for the film, there needed to be evidence.

If someone questioned the diplomats, they needed characters they could actually inhabit.

The operation wasn’t built around a fake passport.

It was built around an entire fake reality.

And for a few critical hours, six people’s lives depended on everyone believing it.

The Real World Is Stranger Than Spy Fiction

Whenever someone tells me something in a spy thriller feels too unbelievable, operations like these immediately come to mind.

Real espionage has involved dead bodies carrying fake documents, secret tunnels, underwater wiretaps, fake Hollywood productions, enormous mechanical claws—and apparently at least one deeply uncooperative cat.

But beneath the absurdity is something much more interesting.

These operations weren’t successful because somebody behaved like an invincible action hero.

They depended on patience.

Preparation.

Psychology.

Technology.

Misdirection.

And people willing to bet everything on the possibility that someone on the other side would believe the story they had constructed.

That’s the part of espionage that fascinates me as a thriller writer.

Because the greatest weapon in intelligence isn’t always the gun.

Sometimes it’s information.

Sometimes it’s trust.

And sometimes it’s simply convincing someone that the world they’re looking at is real.

That’s also part of the DNA behind The Catalogue and the larger V.E.N.O.M. universe I’ve been building.

The operations are fictional.

The organization is fictional.

But the idea that intelligence agencies, governments and individuals can construct elaborate realities around the people they’re manipulating?

History has already proven that part isn’t fiction.

Which of these operations would you have called unrealistic if you’d read it in a novel first?