The Elf Queen

When Jelani tries on a real glass slipper left lying on the sidewalk, it splits in half and out pour dozens of two-inch high "creatures" who scurry away into the shadows. As if that's not bizarre enough, she is soon approached by two men claiming (of all things) to be elves who need her help to rescue their queen. [Book I of the Clan Elves of the Bitterroot Series]