Myth and literature are inseparable: throughout the ages, authors have tirelessly revisited the great mythological stories in their works. This is the case, in particular, of Léa Silhol, a key figure of the French imagination. The author of fantasy draws her inspiration from Celtic folklore and Scottish fairy tale traditions: this dissertation therefore analyzes Celtic mythology in her work, as well as the way it contributes to creating an aesthetic of vertigo. Indeed, the universe that Silhol stages is called the Vertigen, and the different aspects of this vertiginous world are very often double, both enchanting and dangerous, extraordinary and funereal. This book is for any fan of fantasy or enchantment, as well as for any fan of Celtic mythology who wishes to discover its representation in an original work that transports its reader.