Popular science film about Karl Marx. Photos and portraits of K. Marx. Karl Marx's study (London). Museum of K. Marx and F. Engels in Moscow. Excursion to the museum. Covers and pages of Russian magazines "Kolokol", "Vperyod". Manuscripts, articles, books by K. Marx. Documents of the Third Police Department concerning the activities of Karl Marx. V. Zasulich's letter to K. Marx and Marx's answer. The film uses documents from the Institute of Marxism-Leninism under the Central Committee of the CPSU.