I think the description says it all:
Cast out from the magical kingdom of The Realm and into the dying desert of the Sands beyond, Marshal Clint Gulliver and his unicorn Edward have finally found peace in the small and dusty town of Solace. For the first time since leaving The Realm, Clint has dared to be happy, getting hitched to his bride to be, Mai. But when the town faces a deadly approaching enemy, the gunslinger feels compelled unholster his seven-shooters to face it… and the dark magic it brings with it.
From the creators of Yesterday’s Gone (Platt) and Fat Vampire (Truant) comes this reinvention of both the western genre and unicorn lore. Written for children and teens — but complex and awesome enough for adult readers — Unicorn Western is “Harry Potter without wizards, with gunslingers, with talking unicorns and epic unicorn fights, and with more turkey pie.”