Crown of Cinders. Sun and Moon Series, #3

Liora has spent her life learning how to keep doors closed: doors in stone, doors in ritual, doors inside herself. But when a radiant cult-leader named Vespera begins gathering thousands for a "Reunion" under the full moon, Liora discovers the truth too late-this isn't salvation. It's a ceremony designed to take consent, reshape memory, and turn a crowd into a single, chanting mouth. Hunted through markets and mountains, Liora joins forces with Keiran, a prince who refuses to be used as a symbol, and Rowan, a former "proxy" who learns to reclaim their voice.
As the full moon draws near, they race to sabotage the rite from within-rewriting the very structure of the spell so it can't lock without a real, personal answer. But Vespera doesn't need chains when she can make kindness do the work.