It's not been confirmed. As far as we know, Maas was only under contract for three Crescent City books, to complete a trilogy. However, she has previously hinted a fourth could be on its way.

Maas's Crescent City series. Light it up, because the first chapters of Crescent City book three are here early! Bestselling author Sarah J. Maas surprised fans on Thursday by releasing the ...

Her latest book, “House of Flame and Shadow,” the third in her “Crescent City” series, debuted in January — but she says ...