Slay Fae - Undertown Mysteries, #4

The fae don't give gifts, they make deals-and payment's due. A new cafe is coming to Undertown Square! But when a coffee dealer dabbles in black-market magic, bodies pile up and clues point to Emma. (At least that jerk-of-a-detective thinks so.) Emma's sure to find the killer. She's the worst psychic in the world! And she has amazing friends like the gossip ghosts, a professor of applied folklore, a brawny barista, and a hard-boiled cat. But the equinox looms.
An ancient invitation leads to a ballroom filled with elegant waltzes and hungry eyes. When the music stops, the truth lies bare on the dance floor. A trusted ally betrays Emma. A stranger offers her heart's desire. An offhand remark reveals the awful price she paid for her gifts. But she'll only escape if she accepts her birthright and taps her true potential, a power not seen on earth for centuries.