Dr. Horrible, an aspiring supervillain with his own video blog, is attempting to join the prestigious Evil League of Evil (led by the legendary "thoroughbred of sin", Bad Horse), but his plans are usually foiled by the egotistical superhero Captain Hammer. Dr. Horrible's life is thrown for a loop when he falls in love with Penny, a beautiful and optimistic advocate for the homeless he meets at the laundromat.