BEYOND THE CLOUDS (Beyond the Clouds: La fillette tombe du ciel), by Nicke. First published in 2018 and first published in North America in 2020.
PLOT:
Theo has spent his whole life in Yellow Town, an industrial center under a permanently smoggy sky. He works by day as a mechanic, but his nights are spent tinkering and dreaming of visiting the fantastical places he reads about in books. Then one day a strange girl falls from the sky with an injured wing and no memories. Theo and his friends try to nurse her back to health, but after an attack Theo is injured and the girl, Mia, is sick with an unbreakable fever. Her only hope is for Theo to travel into the mysterious forest near the town, in the hopes of finding a doctor with the cure Mia needs.
