The Summer Queen (Buried and the Bound Trilogy #2) by Rochelle Hassan

This captivating sequel to The Buried and the Bound draws readers into the twisted and irresistible world of the Fair Folk--perfect for fans of The Cruel Prince and The Hazel Wood.

As a new coven, Aziza, Leo, and Tristan faced evil and triumphed. All that's left is to put their lives back together, a process complicated by the fallout from painful secrets, the emotional and physical scars they now carry, and the mysteries that still haunt them.
But with the approach of the solstice comes the arrival of strange new visitors to Blackthorn: the Summer Court, a nomadic community of Fair Folk from deep in Elphame. They've journeyed to the border between the human world and fairyland, far from their usual caravan route, to take back something that belongs to them--something Leo's not willing to lose.
Refusing to give up without a fight, he makes a risky deal with the Summer Court's princess and regent. The challenge she proposes sends Coven Blackthorn into the farthest, wildest reaches of Elphame.
But when you play games with the Fair Folk, even winning has a cost. Hardcover; 416 pages