The purpose of the book is a dual one: to detail the nature and results of Tunguska investigations in the former USSR and present-day CIS, and to destroy two long-standing myths still held in the West. The first concerns alleged final solutions that have ostensibly been found in Russia or elsewhere. The second concerns the mistaken belief that there has been little or no progress in understanding the nature of the Tunguska phenomenon. All this is treated by the author in a scholarly and responsible manner. Although the book does present certain unusual findings of Russian and Ukrainian scholars, it is important to stress that this is not a sensational book; it is, rather, a serious exposition of the results of rational investigations into a difficult scientific problem. We are demonstrating the true complexity of the problem that is now entering its second century of existence. Simple meteoritic models cannot explain all the characteristics of this complicated event, and therefore certain so-called unconventional hypotheses about the nature of the Tunguska explosion are to be considered as well.