‘An Unknown Substance’ chronicles Vladimir Kara-Murza’s fight — and his family’s sacrifice

Filmmaker Steven Leckart discusses An Unknown Substance, his documentary about Russian opposition activist Vladimir Kara-Murza, who survived two poisonings before being imprisoned after speaking out against the war in Ukraine. The film evolved during Kara-Murza’s imprisonment to focus heavily on his wife, Evgenia, and her campaign to keep his case in the public eye and secure his freedom. Leckart says that beneath the politics, advocacy and fight for free speech, the documentary ultimately became “a love story.”