Dr. Horrible's Sing-Along Blog is comprised of three acts, lasting around 14 minutes each. In the first act Dr. Horrible is trying to become a super villain and get recognized into the Evil League of Evil, which is led by Bad Horse. He is also in love with Penny, who he met in the Laundromat. And being as shy as he is, he hasn't gotten the courage up to talk to her yet. In order to be a part of the Evil League of Evil, Dr. Horrible has to pull off a major evil act or he will not be voted in. With his luck, as he is trying to steal the Wonderflonium that is needed for his Freeze Ray, he runs into Penny as she is trying to solicit people on the street to open a homeless people shelter. Just when Dr. Horrible thinks the robbery is completed, his nemesis, Captain Hammer, shows up and begins taking credit because he thought he stopped him in the van with his bare hands. Shortly after this, Hammer and Penny start singing to each other.
In the next act, Dr. Horrible is watching them while they are on their dates. The scene goes back to Horrible and Penny talking in the Laundromat and she tells him she is going to go out with Hammer again. This is completely upsetting Horrible. So, Horrible is now back to his blog telling how he is now going to be a part of the Evil League of Evil because he has the Freeze Ray and Wonderflonium. Then he finds out that the LAPD and Hammer are watching his blog and knew ahead of time he was going to do evil and stopped him from succeeding. Now, Bad Horse calls Dr. Horrible and says the only way he can become a part of the Evil League of Evil is to assassinate someone. The story goes on to show Penny and Horrible talking again int he Laundromat when Hammer comes in and tells him his plans with Penny to make him mad and jealous.
In the final act, Captain Hammer speaks at the opening of a homeless shelter where they are going to reveal the statue of him. He is bragging about himself and Penny tries slipping out from embarrassment. While he is still singing, Dr. Horrible blasts Hammer with his Freeze Ray and freezes him as the audience sits in shock. Horrible then taunts the audience and announces that they can't recognize that Hammer's cover is being blown and then he exposes a more deadly gun, the Death Ray. Horrible then aims it at Hammer, but the machine died and at that moment Hammer became unfroze and knocked Dr. Horrible to the ground. Hammer shoots Horrible with the Death Ray and it knocks him back and some of the shrapnel flies into Penny and she ends up dying. In essence, Dr. Horrible has committed the assassination needed to be voted into the Evil League of Evil. The story ends with Horrible wearing his new red coat and going into the room to sit with the other Evil league members, who he is now a part of.
In the next act, Dr. Horrible is watching them while they are on their dates. The scene goes back to Horrible and Penny talking in the Laundromat and she tells him she is going to go out with Hammer again. This is completely upsetting Horrible. So, Horrible is now back to his blog telling how he is now going to be a part of the Evil League of Evil because he has the Freeze Ray and Wonderflonium. Then he finds out that the LAPD and Hammer are watching his blog and knew ahead of time he was going to do evil and stopped him from succeeding. Now, Bad Horse calls Dr. Horrible and says the only way he can become a part of the Evil League of Evil is to assassinate someone. The story goes on to show Penny and Horrible talking again int he Laundromat when Hammer comes in and tells him his plans with Penny to make him mad and jealous.
In the final act, Captain Hammer speaks at the opening of a homeless shelter where they are going to reveal the statue of him. He is bragging about himself and Penny tries slipping out from embarrassment. While he is still singing, Dr. Horrible blasts Hammer with his Freeze Ray and freezes him as the audience sits in shock. Horrible then taunts the audience and announces that they can't recognize that Hammer's cover is being blown and then he exposes a more deadly gun, the Death Ray. Horrible then aims it at Hammer, but the machine died and at that moment Hammer became unfroze and knocked Dr. Horrible to the ground. Hammer shoots Horrible with the Death Ray and it knocks him back and some of the shrapnel flies into Penny and she ends up dying. In essence, Dr. Horrible has committed the assassination needed to be voted into the Evil League of Evil. The story ends with Horrible wearing his new red coat and going into the room to sit with the other Evil league members, who he is now a part of.