The 2019 edition of New Books in Science Fiction kicks off with Peng Shepherd, whose debut novel, The Book of M, tells the story of a mysterious pandemic, the first symptom of which is losing your shadow.

The initial case involves Hemu Joshi, a man celebrating Zero Shadow Day, a festival in India built around one of the two times a year when when the sun, for a few minutes, is exactly overhead and people’s shadows disappear. In Joshi’s case, when those few minutes are over, his shadow doesn’t return.

This strange occurrence, broadcast worldwide, is greeted with delight until more and more people lose their shadows. When the “shadowless” start losing their memories as well, panic ensues.

Just as the cause of the epidemic seems magical, so is its most powerful consequence: the ability of the shadowless to change the world with the power of their imaginations. As a result, the landscape becomes as beautiful as it is terrifying: deers have wings, clouds tinkle like bells, lakes appear overnight, flowers bloom in winter.

The Book of M offers a complex, compelling narrative that combines mystery, magical realism and dystopia. It has garnered widespread praise, earning recommendations from The Today Show and USA Today, and making Amazon’s list of Best Science Fiction and Fantasy Books of 2018. A reviewer on Bustle called it a “post-apocalyptic masterpiece.”

In a world of vanishing memories, Shepherd finds an unlikely hero: a patient with classic amnesia. Unlike the shadowless—who eventually forget everything, including how to speak or eat or breathe—the amnesiac never forgets how the world works. This allows him to take a stand against the seemingly unstoppable pandemic, searching for ways to save the memories of the few who remain.

The narrative follows several characters on distinct but overlapping journeys: the amnesiac as he searches for answers, first about his own life history and then about the epidemic; Ory, as he searches for his wife, who runs away after losing her shadow; and his wife, Max, who is trying to get as far away from Ory as possible for fear that she might inadvertently harm him with the magical powers of her fading imagination. For several of Shepherd’s characters, the worst thing that can happen to them is losing what they inevitably must: their connection to those they love. “Their greatest fear is the people they care about who’ve lost their shadows [will forget] their love and the memories they have together,” Shepherd says.

The book is mum about the pandemic’s cause—as is Shepherd. “I sort of felt like if this really happened to all of us and the world was plunged into this kind of dream-like forgetting state, probably nobody would [know the cause] but everyone would have their theories. Some make more sense than others.”