It's dark. It's earthy. It's foul-mouthed. And, on the evidence of its opening instalment, it's set to be an interesting week ahead following Girl Number 9. It's the latest project from the pen of Doctor Who, Torchwood and Severance scribe James Moran, who this time has turned his talents to a web thriller. Filmed on a tight budget and released online across six five minute episodes, Girl Number 9's first episode is to be found at www.canyousaveher.com (at least from 9pm tonight!)

The thrust of the narrative is that there are detectives - specifically Gareth David-Lloyd and Tracy-Ann Oberman - who have a suspect for a particularly unpleasant kidnap and murder in custody, and they're looking to tie up the case. So far, so routine.

In the interview room, though, said suspect (Joe Absolom) reveals that he has another girl locked away in a cellar somewhere, telling his interrogator that he's got a finite amount of time to find her, and giving him a web address, and a code to type in. Moran's script, understandably, is very quick and to the point, with not a word seemingly wasted, and thus it's not long at all before said website is loaded up, and a tied up girl set against a ticking clock appears on the screen. The games, it seems, have begun.

What's striking about this, even more so considering that you may have your expectations lowered by Girl Number 9 being a web venture, is that the production values are very, very high. There's eery use of music, some very smart direction and a good, solid cast of actors who know their way around a good script (Absolom has the showiest role on the evidence of this first episode, and he's clearly having a lot of fun with it - we're expecting twists and turns ahead, though!). There are also, clearly, some interesting building blocks being slotted into place for the days ahead.

For ultimately, what Moran and his team have managed to put together in the five minutes of episode one is a damn good reason to go back onto the Internet tomorrow night, as the remaining episodes will be uploaded one by one over the coming days.

It's early to say just how successful Girl Number 9 will be, and how satisfyingly it will pan out, but episode one is an enjoyable and promising start.

• James Moran interview