The main character of the film is the creator of the vaccine against plague and cholera, Vladimir Khavkin. In 1892 Anton Pavlovich Chekhov called him "the most unknown person in Russia." And in India, where the scientist saved the lives of more than 33 million people, he was called Mahatma, which means "great soul". The action of the film about the difficult path of a bacteriologist takes place in Russia, Ukraine, France, England, India.