"Between Two Seas" is a fascinating historical book written by the Polish writer Józef Mackiewicz. This novel tells the story of two brothers - Polish Krzysztof and Cossack Ivan, who live in the era of fragmentation of Ukrainian lands between Poland and Muscovy. They find themselves in difficult situations where their friendship and loyalty are greatly questioned. Traveling between two forces of equal quality, the heroes are forced to solve moral dilemmas, because they are sometimes faced with a choice between their native land and personal beliefs. The novel "Between Two Seas" fascinates with its intense story, intertwining facts and artistic origins, and builds an exciting atmosphere of epic events and internal struggles. This book is not only an exciting read, but also an opportunity to better understand the history and culture of the Ukrainian and Polish peoples. "Between Two Seas" is a variety of views on ancient events that invites the reader to think about the meaning of friendship, loyalty and one's own identity.