Nightfall

Nightfall is a fantasy novel by the American writer Shannon Messenger, published in 2017 and the sixth book of the Keeper of the Lost Cities series.

Sophie Foster is a young elf with abilities that other people want to use, and the book finds her grieving and struggling to keep her position while her enemies keep winning. The Neverseen have taken ground, and what is left to Sophie and her friends is a change of approach: new sacrifices, a re-examination of what they thought they knew and, at least in theory, trusting people they have been treating as enemies. Every route they can find leads towards a place called Nightfall, and reaching it means striking a bargain that none of them is happy about. Sophie's abilities, and her memory in particular, are the subject of the search, and neither turns out to be entirely her own.

The problems the characters are dealing with run far back into the history of the Lost Cities.