Antar is an older data analyst nearing retirement, working for the International Water Council in a future New York City. Having grown up in a small Egyptian hamlet and studied in Moscow, he now lives a solitary and heavily regimented life in a nearly empty apartment building. He spends his days fielding queries from his global search system, Ava, and prefers quiet evenings at a local Penn Station donut shop to escape his bleak surroundings.

Murugan is an immaculately dressed former Life-Watch employee who goes missing in Calcutta in August 1995. He is intensely obsessed with the history of malaria research, specifically the official accounts surrounding Ronald Ross's discoveries. His loud, self-satisfied demeanor masks a deep conviction that an unknown group secretly manipulated historical scientific breakthroughs for an entirely different purpose.

Urmila is a young, progressive journalist working for *Calcutta* magazine. As the primary earner for her family, she faces constant pressure from her parents to abandon her career for marriage. She is diligent and observant, traits that serve her well in her reporting and draw her into a complex historical mystery involving Murugan and strange occurrences in the city.

Sonali is a prominent writer for *Calcutta* magazine and a former teenage film actor. She carries an air of natural fame, partly inherited from her legendary stage-actress mother. Though she moves in elite circles and commands attention easily, she forms a genuine friendship with her younger colleague, Urmila, and becomes entangled in the strange events surrounding the Wicket Club and Robinson Street.

Mangala is an enigmatic woman who officially works as a menial cleaner in a 19th-century Calcutta laboratory. Despite her apparent lack of formal education, she exercises quiet authority over the laboratory assistants and demonstrates an advanced, unorthodox understanding of the malaria parasite. She commands deep reverence from a group of followers who gather around her in secret ceremonies.

Phulboni is an acclaimed author in Calcutta who often speaks of the profound secrets hidden within the city's silence. Once a regular in the city's theatrical circles and a crack shot with a rifle, his behavior grew increasingly erratic over the years as he began wandering the streets at night. His early stories, particularly those concerning an elusive character named Laakhan, attract Urmila's journalistic interest.

Ronald Ross is a historical British scientist, poet, and novelist who worked in India during the late 19th century. He is officially credited with discovering how mosquitoes convey malaria to humans. In the present day, his research files, methods, and sudden breakthroughs become the obsessive focus of Murugan's investigations into whether Ross was secretly guided by an outside force.

Lutchman is a dhooley-bearer who becomes an indispensable assistant to Ronald Ross during his malaria research. He possesses an uncanny knack for pushing Ross's experiments in the right direction, such as pointing out specific species of mosquitoes. He is missing the thumb on his left hand and often exhibits knowledge that contradicts his uneducated background.

Laakhan is an elusive, ghost-like figure who appears in various historical anecdotes and literary works across different eras. He is described as an orphaned young boy at a remote railway station in one account, and as a man constantly changing his identity in Phulboni's fiction. He is consistently identified by a deformed left hand and a trailing aura of danger.

Ava is a highly advanced global search system used by the International Water Council. She possesses a relentless drive to catalog and identify unknown objects, often breaking them down into ever-greater refinements of detail. She simulates the rural Egyptian dialect of Antar's youth but displays a strict, almost temperamental focus on productivity, immediately demanding his full attention.

Tara is Antar's neighbor in his otherwise empty New York apartment building. She is a young, birdlike woman who quickly befriends the solitary analyst after being introduced by a mutual acquaintance. She relies on Antar for help securing employment through a rigged computer connection, bringing a rare social element into his regimented life.

Mrs. Aratounian is an assertive, ashen-faced elderly woman who runs a guesthouse on Robinson Street in Calcutta. She is known for her abrupt, commanding demeanor and her previous ownership of a local nursery. She provides Murugan with a room overlooking an old colonial mansion during his stay in the city.

Romen Haldar is a wealthy builder and contractor in Calcutta who wields significant influence at the Wicket Club. He is currently renovating a large, old-fashioned colonial mansion near Murugan's guesthouse. He rose from apparent poverty to great wealth and has a partially paralyzed hand that limits his dexterity.

Elijah Farley is an American missionary doctor and research scientist. He abandons his initial research career in the United States to work at a charitable clinic in the Himalayas, before traveling to Calcutta to investigate early theories about the malaria parasite at D. D. Cunningham's laboratory. His curiosity leads him to uncover unorthodox practices hidden within the facility.

D. D. Cunningham is a large, florid-complexioned doctor who runs a laboratory at the Presidency General Hospital in the late 19th century. He shows little interest in continuing his own research and eventually acts as an obstacle to Ronald Ross's work before suddenly retiring and returning to England.

Urmila's mother is a traditional matriarch who frequently clashes with her daughter over Urmila's demanding journalism career. She places a high priority on her son's success and constantly pressures Urmila to prioritize domestic duties, such as cooking specialized meals, over her professional obligations.

Dinu is Urmila's brother, an exhausted young man who works as a salesman during the day and tutors schoolchildren at night. He is highly anticipated by his family to secure a lucrative sports contract with the Wicket Club, placing immense pressure on both him and his sister.

Grigson is a linguistic surveyor whose diary provides Murugan with crucial historical observations about Lutchman. Grigson's keen ear for dialects and pronunciation leads him to suspect that Lutchman is hiding his true identity and northern origins, a suspicion that puts Grigson in mortal danger.

Maria is a Guyanese woman and one of the regulars who frequents the donut shop where Antar drinks tea. She plays a practical role in Antar's life by introducing him to Tara and convincing him to show her the vacant apartments in his building, effectively breaking his isolation.

Lucky is a young man who works at a newsstand and helps Tara secure her new job by teaching her how to use a laptop. He displays unusual, almost religious deference toward Tara, bowing his head to her feet, which hints at a more complicated dynamic between them.

Tayseer is Antar's deceased wife. She moved into the New York apartment building with him years ago but passed away from an amniotic embolism along with their expected baby, a tragedy that cemented Antar's solitary lifestyle.