The book is dedicated to one of the least explored issues in the work of the outstanding English writer Sir Arthur Conan Doyle (05/22/1859, Edinburgh - 07/07/1930, Crowborough) - the science of ideal investigation of criminal crimes. A. Conan Doyle himself, through the mouth of his main character Sherlock Holmes, called it “the science of deduction.” Using examples from stories and tales about the adventures of Sherlock Holmes and his friend Watson (Watson), it is proved that the “science of deduction” by A. Conan Doyle represents an original synthesis of the principles of abduction (discovery of new knowledge), deduction (deriving necessary consequences from known knowledge) and induction (substantiation of new knowledge), fully consistent with all the requirements of the modern understanding of scientific conclusion. Although the book is intended for the general public, primarily young readers, the author hopes that it will also be of interest to professionals involved in real criminal investigations.