The book of M / Shepherd, Peng

In a future where people's shadows have started inexplicably disappearing and those same people develop a strange new magic power--at the cost of losing all their past memories--husband and wife Ory and Max have escaped the Forgetting and live relatively normally in an abandoned hotel lost in the Virginia woods. Then one day their greatest fear comes to them--Max loses her shadow. Knowing she will soon forget everything about Ory, Max flees. Ory follows, desperate to spend their remaining time together. However, the world outside the hotel has changed, and on their separate journeys each must search for answers about love, hope, and survival.

During a plague-like phenomenon, people are losing their shadows. The change gives them a strange new power, but at a terrible price: it takes away their memories. Ory and his wife Max have escaped the Forgetting so far by hiding in an abandoned hotel deep in the woods. Their new life feels almost normal, until one day Max's shadow disappears too.