Welcome to the documentary from the BBC World Service.

This is the fifth floor.

The fifth floor, you knowsons.

This is the fifth floor at Farnak Amidi Sobeth. This is the fifth floor at the heart of global storytelling with BBC journalists from all around the world.

I'm your host, Faranak Amidi.

The University Library in Tartu in Estonia is a large brutalist complex

surrounded by concrete water fountains and futuristic steel sculptures.

But inside this unassuming building lies a hidden treasure. Rare books worth thousands.

In April 2022, some of these books were stolen. According to Europol, the European Law Enforcement Agency,

this theft was part of a criminal operation that targeted national libraries in 12 countries,

including the Baltic states, Poland, Finland, Germany, and France. It's been described as

Europe's largest book heist since the Second World War. So, who was behind it?

My colleague Nina Nazarova from BBC Russian has been investigating this story and she joins

the fifth floor. Nina, great to have you back on the program.

Hello.

So let's start Nina with the theft in Estonia.

What do we know about it? What happened? So in's start, Nina, with the theft in Estonia. What do we know about it? What happened?

So in April 22, two men walked into the library and introduced themselves as Ukrainian refugees fleeing from the war.

As you can remember, the war in Ukraine just started back then.

So the older one told the librarians that he was helping the younger

one with his university studies. And they asked for eight old editions of Russian offers. And they came

back several times. But later in August the same year, the librarians were doing a written check of the books,

...