Dr. Horrible, an aspiring supervillain with his own video blog, must balance his career and his pursuit of a beautiful do-gooder. He is attempting to join the prestigious Evil League of Evil, but his plans are usually foiled by the egotistical superhero Captain Hammer. Horrible's life is complicated when he falls in love with Penny, an advocate for the homeless. The situation becomes even more challenging when Penny begins dating the boorish, oafish Hammer. Faced with the task of impressing the League, can Horrible overcome his own incompetence to ruin the day, kill the hero, and still get the girl?
