Mortal Queens by Victoria McCombs

They vanish without a trace, disappear into the night . . .

Each year on the center island, one girl is chosen to be the next Mortal Queen of the idolized fae. The mortals praise these lucky girls, but their daughters are never seen again.
The fae realm is eternal night, where disputes are settled by chess matches, power is acquired through the most devious kinds of trickery, and seven illusive kings roam. The fae hide their faces behind masks and guard their glass hearts to keep them from shattering. But beyond the veil of this luxurious paradise, a dark secret simmers, for their Queens have disappeared.
When aspiring artist Althea is selected, she is desperate to avoid the same mysterious fate. With no one to trust, she conceals messages in paintings and receives anonymous replies from a stranger who slowly reveals the tale of a girl who outwitted the fae. Only if she is clever enough will Althea survive the fate of the Mortal Queens. As long as the king who cannot love does not claim her first.