Undead Knights is based on a medieval setting where the player is basically a zombie-creating overlord. There is an option to play as three characters, all who were brutally murdered by the order of the king and want revenge on him.
The story follows a trio of knights: Romulus Blood (Keith Ferguson), a human knight and former head of the House of Blood who made a Faustian bargain with an unseen demon known as The Beast (Steve Blum), along with his younger brother Remus (Andrew Kashino) and Remus' wife and princess of Cavalier named Sylvia Gradis (Megan Hollingshead) while they are at the end of their lives after the entire House of Blood is slaughtered under the orders of the king Kirk Gradis (Also voiced by Steve Blum) and his charismatic, tyrannical wife Fatima (Wendy Braun). Over the course of the game, The Beast grants each of the three characters a second chance at life as necromancers with the ability to turn their still living enemies into undead soldiers.
Source: Wikipedia, "Undead Knights", available under the CC-BY-SA License.