NPH portrays Billy, or Dr. Horrible when he's being beaten up by Fillion's Captain Hammer. Billy silently pines after Penny (Day), and when he puts on his lab coat and goggles he's planning how to get her heart by giving her "the keys to a shiny new Australia." During the short web series his current plan is to complete his freeze ray, which he will use to "find the time to find the words to" tell Penny how he feels about her.
He also intends to use it to cement his entry into the Evil League of Evil, an organization headed by Bad Horse, the Thoroughbred of Sin.
Billy's plans go horribly awry, however, when Captain Hammer, who is a jerk all the time, rescues Penny from a runaway van and they begin to date.
But what happens? You'll have to find out after you buy your own copy through Best Buy for $9.99. If only you had been a little faster; at one time it was completely free online. Alas!