Neil Patrick Harris stars as Billy, A.K.A. Dr. Horrible, a budding super-villain whose plans for world domination continually go awry. His two goals: getting accepted into the Evil League of Evil, and working up the guts to speak to his laundromat crush Penny, played by Felicia Day. The only thing standing in his way is Captain Hammer, Billy's superhero arch-nemesis played by Nathan Fillion With one big score, Billy could get into the E.L.E. and earn the respect of Penny, but only if he can keep her away from the dashing Captain Hammer...