A trailer for the third season of the BBC's sci-fi television show Torchwood has been released. This season Torchwood will run as a five-episode mini-series and may air in a single week when broadcast in the UK (the first two seasons of Torchwood were 13 episodes each). Season 3 will be called Torchwood: Children of Earth, and since it's one story, it will have no individual episode titles.

The only cast members who appear to be returning are John Barrowman (Captain Jack Harkness), Eve Myles (Gwen Cooper) and Gareth David-Lloyd (Ianto Jones). Myles and Ianto appeared together in the Doctor Who Season 4 two part finale (The Stolen Earth / Journey's End). Owen Harper (Burn Gorman) and Tosh (Toshiko Sato) were killed off in Season 2.

Torchwood producer Peter Bennett told Digital Spy that "As far as the storylines are concerned, it's allowed us to see a whole new side of what's left of our regular characters and learn a whole lot more about their lives."

Bennett said Torchwood's Season 3 will be "about a government that did a deal with aliens back in the '60s, and they're now dealing with the consequences of that deal when the sins of their past come back to haunt them.

"This series takes Torchwood on a much darker journey," he said, "but it's still Torchwood. It's exciting, action-packed, and we've still got a lot of fun running through it."

Gwen's husband Rhys (Kai Owen) is likely to take on an expanded role.

"He was always on the fringes anyway but he takes a much more active part in the storyline now. And we've got a new young lady who helps the team".

I must admit I was steadily losing interest as I watched Season 2, so I hope this change is for the better. The episode featuring Gwen being impregnated by an alien on her wedding day was the low point for me. Perhaps focusing their creative energies into a shorter 5 episode season with fewer cast members will allow them to raise the excitement level.

And what about a fourth season? When Bennett was asked about a rumour that John Barrowman would not be returning after the end of the third series he said:

"I've not heard him say he wouldn't want to stick around after a third series, so I'm not sure where that's come from. But he certainly never mentioned it to us or on set. It wouldn't be the same without him obviously."

With that kind of a response, they're at least thinking about Season 4.

Torchwood Season 3 will be broadcast in March 2009 on BBC1. BBC America will broadcast the show shortly afterwards.

You can watch the Torchwood extended Season 3 trailer below.