The film is about the discovery in 1962 by V. A. Karnaukhov, G. M. Ter-Akopyan, V. G. Subbotin, and L. A. Petrov of proton radioactivity. The detection of a new type of radioactive decay of atomic nuclei – proton emission – significantly expanded our understanding of the properties of nuclei and the limits of their possible existence in nature. A fundamentally important fact is that the theoretical analysis of proton radioactivity confirmed the validity of the models widely used in traditional nuclear physics and the possibility of describing new previously unknown phenomena based on them.