"The Day of the Beast" is a novel by Zane Grey. The story follows the protagonist, Milt Dale, a former cowboy who sets out to avenge the murder of a young girl he had once promised to protect. Dale's quest takes him to the remote wilderness of the Grand Canyon, where he finds himself caught in the midst of a conflict between two rival cattle barons and their feuding families. As Dale delves deeper into the conflict, he discovers a dark and treacherous world of greed, betrayal, and violence. Along the way, he falls in love with a beautiful young woman named Thiry Maret, who is caught in the middle of the feud. Together, they must navigate the dangers of the canyon and outsmart their enemies if they hope to survive. Throughout the novel, Grey's vivid descriptions of the rugged terrain and harsh conditions of the Grand Canyon bring the setting to life. The novel also explores themes of honor, loyalty, and the struggle between good and evil. With its fast-paced action and thrilling suspense, "The Day of the Beast" is a classic Western tale that continues to captivate readers today.