Dr Horrible online today!

Joss Whedon’s new made-for-the-web musical, Dr Horrible’s Sing-a-long Blog launches today, as the first of three “acts” goes online. It’s the story of the titular low-rent supervillain (played by Neil Patrick Harris), whose plans for world domination are regularly scuppered by the heroic Captain Hammer (Whedon regular Nathan Fillion).

When we spoke to him a few months back, Whedon described the show as “a classic talk-then-break-into-song musical. The songs are a pop/show hybrid – that is, the sound is poppy and (hopefully) catchy, but the lyrics progress rather than just repeast. The songs move the story. But ya can’t stop humming ‘em! (Legally. Hum-stoppage will result in up to six months in WoW as some lame healer.)”

Following today’s debut, the next two episodes will appear on the official Dr Horrible site on Thursday 17 July and Saturday 19 July. But you’ll have to get your skates on. They’ll only be available to watch for free until Sunday 20 July. After that they’ll disappear, though Joss does plan to make them available for paid download and DVD. You can read more about “the masterplan” here . There’s also a Dr Horrible comic .