Księga Tajemnicza. Prolog is the debut album of Polish hip-hop group Kaliber 44, released in 1996, on S.P. Records. The album is one of the most influential releases in the history of Polish hip-hop. The album was entirely produced by Kaliber 44, except two tracks that were produced by Rahim from 3xKlan and Jajonasz. The sound of Księga Tajemnicza. Prolog is dark, gloom and the minimalist. An important role during the recording sessions was a marijuana that members of Kaliber 44 smoked. They called themselves "the Knights of Mary" (Mary in the Polish slang means marijuana).