At the end of "Children of the Earth" Cpt. Jack Harkness left Earth because there was nothing there for him anymore after the deaths of Tosh, Owen, Ianto and his grandson. Gwen was pregnant and quite happily married with Rhys and so he hitchhiked into the galaxy.
Now the word "Torchwood" surfaces in an e-mail in Langley and only minutes later the "miracle" happens - nobody dies. But not in the way Jack didn't die, but simply by not dying no matter how grave or hurtful the injury. A health-care catastrophe develops on a global scale and a new Torchwood develops to meet the new threat to humanity's soul.
This season is quite complexedly written and spans history over 90 years and the whole planet. There are wheels within wheels and a lot of them are still turning and there might be more than are known until now, so that a fourth season is sincerely wished for from my side. I laughed out loud, sacrified sleep, went through an emotional wringer and was very happy to put in the first DVD again after watching the last extra (by the way, the extras are quite 08/15-stuff, so nothing much to write home about).
Points of critic? Mmmh, surely addictive - should carry a health-warning. Ah, and the intros to each episode spoken by "Cpt. Jack" and Russell T. Davies are something to fast-forward over. Especially when you watch the episodes one after the other.
Great show. Really liked the breadth and depth and the many biblical allusions. And are hoping that Mr. Davies does go for a fourth season.