Green debuts with an electrifying science fiction thriller that chronicles the aftermath of a pandemic. Rachel Jackman struggles to keep her family afloat in a London ravaged by the J5X virus, which has proven fatal to many. Rachel's young son, Billy, contracts the virus but makes a miraculous recovery, spurred back to health by the urging of his new imaginary friend, Delfy, who encourages him to eat and rest. At first, Rachel doesn't think much of Delfy, but Billy, restored to full health, soon becomes obsessed. Under Delfy's unyielding influence, Billy lashes out against his family with increasing violence, prompting Rachel to seek professional help. She takes him to psychiatrist Graham Watson, who is studying a group of children who all had the virus and all recovered with the help of imaginary friends. Meanwhile, Rachel's daughter, Nina, who's training to be an astronaut, discovers a clue about the virus's origins wrapped up in a web of corporate secrecy. Green's truly terrifying tale wisely focuses on the human element in the midst of a global catastrophe. Green makes it easy to feel for Rachel as her family threatens to collapse and to root for Nina as she pursues her dream, and the sharp, empathetic characterizations make the mysterious threat of Delfy all the more chilling. Green is sure to make a splash. Agent: Hillary Jacobson, ICM Partners. (Oct.)

Malevolent inner voices plague young pandemic survivors in near-future London. The J5X virus has killed millions worldwide and--unlike Covid-19--is particularly lethal to children under 10, so when 6-year-old Billy Stevens falls ill, his mother, 43-year-old divorcée Rachel Jackman, braces for the worst. After weeks of steady decline, however, Billy miraculously recovers and soon begins chatting nonstop with an invisible entity dubbed Delfy. Rachel assumes that Delfy is something Billy created to cope with the boredom of his convalescence, but the rest of the family isn't so sure. Rachel's partner, Al, and Billy's 16-year-old sister, Nina, fear Delfy is a post-virus complication. Rachel's mother, Orla, becomes convinced that Billy is possessed after "Delfy" tries to strangle her. Government health insurance doesn't cover child psychiatric care, and Rachel and Al are broke, so when Billy's violent behavior escalates, Rachel persuades her ex-husband, Henry, to pay for a consult with professor Graham Watson, whose website advertises a specialization in "post-flu imaginary friends." Unbeknownst to Rachel and company, Graham has a secret underground clinic full of kids like Billy. Pseudonymous author Green's debut suffers somewhat for her haphazard incorporation of the J5X outbreak; the characters' cavalier attitude toward disease prevention strains credulity, particularly given current events. Although a subplot that spotlights the affordable housing crisis feels more carefully considered and Rachel's mounting panic rings true, a deeply silly coda undercuts the tale's largely gratifying climax and denouement. A fusion of horror and social commentary that chills but proves too uneven to truly terrify. Copyright (c) Kirkus Reviews, used with permission.