Adapted from Agatha Christie’s novel, *The Pale Horse* follows Mark Easterbrook, a charismatic antique dealer whose life unravels after a
police investigation connects him to a mysterious list of names found inside the shoe of a dead woman, Jessie Davis. Initially, Mark is unconcerned, focusing instead on his complicated personal life: his wealthy first wife Delphine has recently died under suspicious circumstances, and he is preparing to marry his ambitious new lover, Hermia. However, panic sets in when Mark discovers his own name on the infamous list.His search for answers leads him to the remote village of Much Muchnden and an ominous residence called The Pale Horse, inhabited by three eccentric women—Sybil, Bella, and Thyrza—who are widely rumored to be modern-day witches. Meanwhile,
police inspector Lejeune investigates a series of bizarre, sudden deaths sweeping London, where victims exhibit no signs of violence or poison, yet their hair falls out entirely. It soon transpires that people are paying a hefty sum to The Pale Horse to have their enemies mysteriously murdered via dark forces.Driven by paranoia and a desperate need to clear his name, Mark becomes obsessed with the cottage and the witches. He experiences terrifying hallucinations, memory loss, and escalating dread, leading him to suspect that he is either losing his mind or being targeted by supernatural forces. As the body count rises—including the murder of his friend David Ardingly and the sudden illness of Hermia—Mark’s reality fractures completely. He begins to question everyone around him, suspecting that someone close to him has cursed him.The chilling truth is eventually unveiled, proving to be rooted in cold, calculated science rather than witchcraft. A brilliant chemist named Osborne has engineered a lethal thallium poisoning method, administering it secretly to victims while using the witches' reputation for black magic as a psychological smokescreen and deterrent. Osborne’s motivation is purely financial and sociopathic; he orchestrates the murders for profit and to eliminate anyone who stands in his way.In the gripping climax, Mark confronts Osborne just as the conspiracy collapses under the weight of police scrutiny. Although Mark survives the ordeal physically, the psychological trauma leaves him fundamentally changed. The series concludes on a deeply unsettling note, suggesting that even though the supernatural elements were a hoax, the capacity for human malice is just as dark and destructive as any ancient curse.