This is The Guardian.

Today, the extraordinary story of Russia's spy families.

One evening in August 2024, a plane lands at Moscow's Vnukova Airport, the doors open, and a series of people come down the steps towards a red carpet.

And among these people are a family of four. There are Argentinians. She's called Maria Meier.

He's called Ludwig Gish, and they're there with their two children.

And who is waiting for them, but Vladimir Putin, who hands Maria a big bouquet of flowers.

She looks shocked, overwhelmed, delighted.

The children look confused, overwhelmed,

don't quite know what's going on.

Putin bends down and kisses both of the children

and says to them,

Buenos nos notches.

The couple had just been released from a Slovenian prison after spending about a year and a half there,

and they were returned to Russia as part of a prisoner exchange because their real names were not Maria Mayer and Ludwig Gish.

They were in fact Anna and Ludwig Gish.

They were, in fact, Anna and Artion Dulcev.

And they were a couple of illegals, which is the Russian term for deep cover spies, who spend years and years posing as foreigners, in their case, as Argentinians and living in a foreign

country. The children were apparently only told that their parents, and indeed the whole

family, was in fact Russian and not Argentinian, on the plane to Moscow.

Sean Walker, the Guardian's former Moscow correspondent, and now our man in Eastern Europe, has been obsessed with spies like the Daltsev's for a decade now.

So obsessed, in fact, that he's now written a book about them.

It's called The Illegals, and it tells the story of these

...