Felicity Peridot, avid journalist, mild-mannered unicorn, moonlighting vigilante, must take up her alter-ego, The Mysterious Mare Do Well, to combat her most dangerous opponent yet! An enigma, Checkmate, who single-hoofedly turned the underground criminal world of Manehattan upside down. With a young ward at her side, will she meet her downfall at the hooves of Checkmate?