Set in Victorian England, The Essex Serpent follows London widow Cora Seaborne who is freed from an abusive marriage. Moving to the small village of Aldwinter in Essex, she becomes intrigued by a local superstition that a mythical creature known as the 'Essex Serpent' has returned to the area. She forms an unlikely bond with Will Ransome, the village pastor, but when disaster strikes, the locals accuse her of attracting the creature.