The Essex Serpent is a novel by Sarah Perry, released in 2016. Set in 1893, it tells the story of Cora Seaborne, a recently widowed woman with a burning interest in the natural sciences. Escaping London, she visits a small village in the Essex countryside. There, she finds a population in thrall to the local legend of a sea monster lurking in the nearby estuary and a village priest who is desperately trying to dissuade his congregation of this belief.

The book begins on New Year’s Eve. A drunk young man wanders down to the shore of the Blackwater estuary with the intention of swimming. He senses something strange in the water and then disappears. In crowded London, a skilled surgeon named Dr. Luke Garrett (nicknamed the Imp for his diminutive stature) travels to the funeral of a former patient, Michael Seaborne. Garrett has fallen in love with Michael’s wife, Cora, who he grew to know while treating her husband. He sensed an unhappiness in the marriage and became acquainted with Francis Seaborne (Cora’s son) and Martha (Francis’ nanny). Cora has developed a burning passion for the natural sciences. Francis is known for his strange behavior; he collects objects—his “treasures”—from everywhere he can. Cora watches the funeral with an “interested detachment” (20) and afterward, she walks alone through London. That night, Cora falls asleep “clutching her Dorset ammonite” (25).

Garrett talks with George Spencer, his closest friend and a fellow doctor. Cora has departed for Colchester; Martha loathes the rural location, but Cora enjoys it. They meet Thomas Taylor, a disabled man who watches over a stately home ruined by a local earthquake. Taylor tells them the story of the Essex Serpent, a “great creeping thing […] more dragon than serpent” (35). Cora meets her friends Charles and Katherine Ambrose on the street; via letter, they introduce Cora to William Ransome, a local vicar in the village of Aldwinter in the countryside. Will has been struggling to convince his congregation that the Serpent is a myth. Cora moves to Aldwinter and begins to search for signs of the monster, believing it might be a hitherto undiscovered living fossil. One day, while walking alone on a path and reflecting on how little she loved her husband, Cora hears a sheep trapped in mud. She helps a strange man free the sheep. Will’s daughter, Joanna, and Joanna’s friend Naomi Banks cast a spell near the shore to ward off the Serpent. Will arrives, covered in mud, and takes them home.

Stella Ransome, Will’s wife, writes to Cora and invites her to dinner. Francis, Martha, Charles, and Katherine are also invited. Garrett and Spencer visit Colchester; Martha explains to Spencer how interested Cora has become in the Essex Serpent. Martha is a socialist, and Spencer is a privileged member of the bourgeoise; they talk about social housing in London. Stella prepares for her dinner party and reflects on her three children and how much she loves her husband. When Cora arrives, the two women are immediately friendly with one another. Will arrives later and, on meeting Cora, both fall into fits of hysterics: Will is the strange man whom Cora helped to free the sheep from the mud. Dinner conversation eventually turns to the Serpent. A local resident, Cracknell, believes that the creature took one of his goats. Will does not believe the Serpent exists, but Cora disagrees. The next day, Cora attends the service in the local church. At one point, she cannot help but cry. On exiting the church, she encounters a disheveled Cracknell and flees. Stella watches the congregation and reflects on her dreams.

Cora, Martha, and Francis move to Aldwinter. Garrett performs an experimental surgery and saves the life of Edward Burton, who has been stabbed in the heart. Cora explores Aldwinter though finds no trace of the Serpent. One morning, she meets Will on the common. She joins him at the rectory, and Stella serves cake before retiring to bed due to illness. Will and Cora, left alone, talk at length. They go for a walk and, while near the estuary, see a ghostly ship flying through the sky far above the horizon. They hold hands. In the coming days, Will writes to Cora with a scientific and heavily researched explanation for what they saw.

Naomi and Joanna grow more distant. Cora, feeling increasingly at home in Aldwinter, regularly visits Will, and they spend a lot of time talking. Stella’s flu lingers. Garrett’s successful surgery turns him into a celebrity, but he remains poor. He also worries that he has become sidelined in Cora’s estimations. Martha and Garrett share a concern about Cora’s budding relationship with Will. Inspired by Martha, Spencer becomes very interested in the political issue of social housing. Will and Francis have a conversation on the nature of sin. Cora gives a talk to the local school class. When she asks them to draw serpents, a sudden, crazed hysteria falls over the children, and one girl falls from her chair and hurts herself. When Garrett travels to Aldwinter, the incident has deeply affected those involved. Cora is concerned and guilty; Joanna has not laughed since. Cora and Stella convince Garrett to hypnotize Joanna to find out the truth about what happened. Will arrives midway through the session and is furious. He drags away his wife and child. Martha visits Burton as he recovers from Garrett’s surgery; he reveals that he had bullied Samuel Hall, the man who stabbed him, and feels as though he himself deserved to be hurt. Martha admits that she feels guilty for manipulating Spencer’s romantic interest in her to achieve political goals. Cora spends time in Colchester; she is “in disgrace” (169) with Will, who still has not forgiven her. She writes to Will and refuses to apologize. He tells her that she is forgiven, though his words seem hollow. Cora hopes that Garrett will examine Stella’s perpetual medical woes.

As summer arrives, Aldwinter seems to return to normalcy. Cora plans a midsummer party, and everyone is invited. Spencer recruits Charles to further his newfound political agenda. Cora walks alone through the countryside and reflects on her relationship with Will and the rest of the Ransome family. Stella develops an obsession with the color blue. She believes that her flu is actually consumption but has not told Will. They arrive at the party, and there seems a distance between Cora and Will. In the evening, Joanna begins to play a waltz on the old piano. The guests dance and, eventually, Will and Cora are paired together. They share a strange moment, noticed by most in the room. The party dissolves shortly after. Cora goes to bed, and Will walks alone on the common, furious with himself. Sharing a concern about Will and Cora, Martha and Garrett bond. They sleep together.

Francis exits the house in the night and walks to the shore, thinking about Stella and sympathizing with her collection of blue objects. At the shore, he finds Cracknell. The man begs Francis to get help, but Francis knows that Cracknell is dying; getting help would be a wasted effort. He sits down beside Cracknell as the dawn rises. Cracknell dies. In the early hours of the morning, Cora writes to Will and says she will return to London for a while. The next day, Will is called to the shore where Cracknell lays dead. He shares a correspondence with Cora and admits his longing for her. He refuses to be ashamed of his feelings. She does not reply. Stella visits a doctor; both Will and Garrett are present. She has consumption.

In Aldwinter, Naomi goes missing. The village believes that the Serpent killed Cracknell. Everyone is scared. Stella begins to write in a blue book. Will tries to remain positive. Cora reads Will’s letters but does not reply. In London, she meets often with Garrett. Martha spends more time with Burton. Hall watches his victim, plotting in the shadows. Garrett writes to Cora and admits that he loves her.

Charles, Spencer, Martha, and Garrett explore the slums of Bethnal Green. Political changes are coming, Charles assures Martha. Hall watches from an alley and attacks Garrett, blaming him for saving Burton’s life. Hall is killed during the attack. Garrett survives, but his hand is severely cut. Cora regrets her time in London and misses Aldwinter. After Stella’s diagnosis, the Ransome children move in with Charles and Katherine. Meeting with Cora, Katherine asks her about Will, and Cora insists that they simply enjoyed one another’s company. Struggling to come to terms with what happened with Will, she is also annoyed by Garrett’s letter. She writes an angry reply. A day later, she finds out about the attack and sends a second, more apologetic letter. Spencer operates on Garrett’s injury, disobeying Garrett’s request for no anesthesia. Spencer cannot save Garrett’s hand, and Garrett believes he has been betrayed. After the surgery, he reads Cora’s letters and is “shattered” (232). After three weeks, he knows he will likely never perform surgery again and sinks into a deep depression.

In September, the fear of the Serpent reaches fever pitch. The characters struggle with their various unhappy problems; only Stella seems content, though her condition worsens. Burton and Martha grow closer together. A vile smell permeates all of Aldwinter. Will leads the villagers to the beach and finds a giant rotting fish with a gut full of tapeworms. After being admonished by Katherine, Cora agrees to return to Aldwinter. She visits the rectory but finds only Stella. They talk a while, and Stella and Francis form a strong bond. Later, Cora writes to Will, and the two spend time together. They walk together, rekindle their friendship, and then have sex in the forest. Garrett contemplates suicide but cannot bring himself to do it, fearing the effect it will have on Spencer. Francis sees something on the shore and writes to Stella, requesting a meeting. Cora writes to Will, telling him she feels no guilt for their time together in the forest. Francis meets with Stella, and the two hatch a plan. Stella gives Francis detailed instructions of what to do. Charles and Katherine bring the Ransome children to visit their parents. In Colchester, Joanna notices that Naomi is pretending to be a boy and is staying with Taylor. Naomi agrees to return to Aldwinter, where she reunites with her father. When the family reunites, Will speculates how this will affect him and Cora. Stella lays down to sleep while Will struggles to come to terms with Cora’s letter.

At precisely five o’clock, Francis goes to the shore. Joanna and Naomi walk along the marshes together. They hear a strange noise and think it might be the Serpent. The Serpent is revealed to be Naomi’s father’s lost boat, covered in barnacles and scraping on the shore. Joanna goes to get her father; Francis watches from afar. Will is dragged to the shore by Joanna. He understands and takes the two girls home. When he arrives at the rectory, Stella is missing. He remembers the blue stones by the boat and rushes to the shore. They lift the boat and find Stella inside, laying in the water, ready to push herself out into the estuary and die. They carry her home. Stella tells Francis to cast her blue stones into the Blackwater.

Banks burns the ruined boat. The Ransome children remain with Charles and Katherine. With Martha set to marry Burton, Spencer loses enthusiasm for his political activism. He buys the slums in Bethnal Green and refuses to raise the rent. Spencer and Garrett perform surgeries together, using Spencer’s hands and Garrett’s theories. Will tends to his congregation and cares for Stella, who is making progress in her recovery. He does not feel the need to write to Cora. The novel closes with a letter from Cora to Will. She has returned to London. Francis is away at a boarding school. Cora believes that solitude suits her. She tells Will that she loves him and is content without him. She hopes that he will come to her quickly.