“For so many years, two persons were inside of me,” says Deniss Metsavas, a former Russian spy. In a new documentary from The Atlantic, Metsavas tells the disturbing story of his double identity for the very first time.

Metsavas, who is ethnically Russian, grew up in the U.S.S.R. After the collapse of the Soviet Union, he learned the Estonian national anthem for the first time. He joined the Estonian Defense Forces, where he served as a trusted officer for 20 years. Now he is serving 15 years in an Estonian prison for treason.

Everything changed in 2007. On a trip to visit relatives in Russia, Metsavas says he was ensnared by Russian intelligence officers who had collected kompromat, or "compromising material,” on Metsavas, in order to blackmail him into engaging in espionage for the Russian Federation. The officers worked for the GRU, Russia’s largest foreign-intelligence agency.

For years, Metsavas navigated his disparate allegiances. He got married and started a family. But as he grew in prominence in the Estonian Defense Forces, his Russian handlers began to demand highly classified information on Estonia’s involvement with the United States and NATO, specifically with regard to weapons. Metsavas tried to extricate himself, only to find that his handlers would stop at nothing to obtain the intel—including ensnaring a family member in the increasingly dangerous situation.

For more on Metsavas’s story, read Michael Weiss’s story “Estonian, Russian, Soldier, Spy.”