The Undying Monster (1922) is a horror novel by Jessie Douglas Kerruish. Recognized as a groundbreaking work of lycanthropy, or werewolf fiction, The Undying Monster was adapted into a successful 1942 horror film starring James Ellison, Heather Angel, and John Howard.

Haunted for generations, the Hammand family has grown accustomed to tragedy. Early deaths, suicides, and gruesome injuries plague their family tree, and they have long been regarded as pariahs in their rural English community. When Oliver Hammand survives a vicious attack while walking in the woods one night, his sister Swanhild resolves to put an end to the ancient curse. Seeking the guidance of Luna Bartendale, a powerful psychic, Swanhild convinces her brother to join her on a journey of discovery and danger to not only free their family from its dreadful cycle, but to save their own young lives. Together with Luna, they scour ancient archives, investigate ruined graveyards, and search for whatever clues they can find. As they delve deep into the heart of their family's mystery, Oliver falls deeply in love with Luna. Led to the edge of existence itself, the trio find themselves face to face with a horror too terrible to imagine. The Undying Monster is a masterpiece of werewolf fiction by a largely forgotten writer of popular romance, mystery, and horror novels.

With a beautifully designed cover and professionally typeset manuscript, this edition of Jessie Douglas Kerruish's The Undying Monster is a classic of English horror fiction reimagined for modern readers.