In 1893 London, Cora Seaborne is liberated from her unhappy marriage by her husband's death. Seeking fresh air and reprieve in Essex with her son, Francis, and protective friend, Martha, Cora hears tales of a mythical beast, the Essex Serpent, said to be back after centuries. A curious amateur naturalist, she's drawn to uncover the creature's truth. Cora meets William Ransome, a vicar who sees the serpent scare as a diversion from true faith. Despite their opposing views, Cora and William form a compelling bond, leading them into a deep relationship that defies expectations and alters their lives. As Cora delves into the mystery of the Essex Serpent, her past pursues her, culminating in unforeseen consequences. 'The Essex Serpent' weaves a rich tapestry of science, religion, and love, unraveling the unexpected forms affection can take.