Sailing ships, stars, angels and executioners — The Mark of Cain chronicles the vanishing practice and language of Russian Criminal Tattoos. Captured in some of Russia’s most notorious prisons, including the fabled White Swan, the film traces the animus of the flowers of this carnal art by way of the brutality of its origins- the penitentiary and the criminal environment. Incisive interviews with prisoners, guards, and criminologists reveal the secret language of The Zone and The Code of Thieves of the vory v zakone. As early as the 1920′s, Russian prisons and Gulag began to attract the attention of researchers. The prisoners of the Stalinist Gulag, or “Zone,” as it is called, developed a complex social structure that incorporated highly symbolic tattooing as a mark of rank. The very existence of these inmates at prisons and forced labor camps was treated by the state as a deep secret, and their tattoo art was considered a forbidden topic.