Hitting the Internet this week only is a new miniseries from Joss Whedon, the multi-talented creator of such beloved television series as Buffy the Vampire Slayer, Angel, and the criminally short-lived Firefly. If the combo of Neil Patrick Harris, musicals, superheroes vs. villains, Nathan Fillion, and Joss Whedon co-writing and directing sounds good to you, rejoice! Thanks to the writer’s strike, he and several of his compatriots got frustrated, bored, and inspired, and rather than let their creative juices fester under the burden of not being able to write for film or TV, they came up with a plan for an Internet-distributed production, the “supervillain musical” Dr. Horrible’s Sing-Along Blog.

Whedon had just gotten the ball rolling on his upcoming new series, Dollhouse (headlined by former “Buffyverse” star Eliza Dushku), when the Writers’ Strike hit; not one to remain inactive for long, he got together with his brothers Zack and Jed, as well as the latter’s fiancée, Maurissa Tancharoen, to pen what became Dr. Horrible’s Sing-Along Blog. The tale of a misunderstood supervillain who longs for the love of a sweet young woman at the Laundromat, while also being constantly thwarted by the outwardly heroic egomaniac Captain Hammer, the miniseries is presented in part as a video blog by Dr. Horrible (with him speaking directly to the camera), and partly as a spoof of superhero adventures — but with musical sequences galore. To produce this little miniseries, Whedon gathered a crew of friends, family, and previous colleagues, and funded the production himself. To fill in the starring roles, Whedon cast both actors he had previously worked with — Firefly’s own “Captain Tightpants,” Nathan Fillion, and the relatively unknown Felicia Day, who had played one of the potential slayers, Vi, during the final season of Buffy — as well the prodigiously talented former Doogie Howser star and current sitcom sidekick extraordinaire Neil Patrick Harris.

When the official website launched earlier this year, it contained only the mysterious promotional poster shown above, with Dr. Horrible mostly in shadow. Nonetheless, a fansite sprung up shortly thereafter. A teaser trailer finally hit the web in late June, getting the buzz going even more.

Joss Whedon soon released a statement of his “master plan” for his ravenous fans, explaining that Dr. Horrible’s Sing-Along Blog would be streamed for free online for one week only, in three installments. Act I would hit the web Tuesday, July 15, followed by Act II on Thursday, July 17, and ending with Act III on Saturday, July 19. Fans would be able to enjoy this free release of the miniseries through Sunday, July 20, at midnight. Meanwhile, it would also be made available for purchase on iTunes (for $1.99 per installment), which would continue on into the foreseeable future, with an eventual DVD release in the works (including tantalizing extras, of course).

Thus far, the first two acts have been released for online viewing. (They each run about 13 minutes long, so the whole thing all together should be a 40-minute or so viewing experience.) As a longtime Whedon fan as well as an admirer of Neil Patrick Harris’ current scene-stealing work on How I Met Your Mother, I was hoping for something pretty great, and that’s just what I got. Act I starts off just a little slow, with Harris’ Dr. Horrible video-blogging to his fans, but once it breaks into a cute musical number, and especially when Fillion’s hilarious Captain Hammer shows up, everything is quite fun. The musical numbers are very reminiscent of Whedon’s famed musical episode of Buffy the Vampire Slayer, “Once More, With Feeling,” with catchy melodies sung by the actors themselves, who, despite have varying degrees of singing ability, are always endearingly entertaining. But amazing singing isn’t really the point — it’s relatable emotions mixed with extraordinary situations and Joss Whedon’s unique, witty writing. Act II continues the story along, builds tension, and with the first act already having set up the characters, has a lot of fun with them! Harris and Fillion have met their match in one another, filling in their roles perfectly and making their onscreen rivalry all the more amusing. They’re both funny in different ways — Harris is slightly understated as the unexpectedly meek villain, but he still packs a comedic punch, and Fillion is campily hilarious as the macho “hero” with a less than valiant agenda. Relative newcomer Felicia Day is sweet and charming as Penny, the object of Dr. Horrible’s affection. So far, so good! I’m excited to see how things conclude. For now, check out the first two acts, and catch that last one on Saturday.

Behold, Dr. Horrible’s Sing-Along Blog!

(For an even better viewing experience, switch to full-screen mode via the button on the lower right-hand side of the video window once you’re on the page for each installment.)