brought to you by Aspire Mungfront on ITVX, a six-part drama of friendship and betrayal,

starring Damien Lewis and Guy Pierce. The coldest war is within. Aspire Mungfront,

stream free on ITVX.

Welcome to True Spies. Week by week, mission by mission. You'll hear the true stories

behind the world's greatest espionage operations. You'll meet the people who navigate this secret world.

What do they know? What are their skills? And what would you do in their position?

This is True Spies. These individuals appeared to have suffered a head injury,

but there was nothing in their reported medical history to suggest they had a prior head injury.

And hence, this initial syndrome was referred to as the macular concussion.

This is True Spies. Episode 97. Havana Syndrome Special.

The room is literally spitting. I'm about to be sick. Years were ringing headache,

but I didn't really know. And so I kind of just stumbled around the room,

ended up making it back to the bed. Hoping that by morning, this would wear off,

but unfortunately, it did not. I understand the opioid crisis. I understand addiction now,

because it would be so easy for me to go that route, to just ease the pain.

Some enemies are invisible, silent, out of sight, but never out of mind.

I don't think insider diplomatic or intelligence community that there are many people

who do not believe this as some sort of attack. It's now clear that it's doing serious damage

and having brain injuries to American citizens. And so at this point,

it has to be looked at as a weapon.

A weapon that could change the face of espionage and global warfare as we know it.

These are not generalized effects that occur in individuals who may have been exposed

...