Torchwood: Miracle Day is the fourth series of the British science fiction television programme Torchwood, a spin-off from the long-running show Doctor Who. In contrast to the first three series, which were produced by the BBC, the fourth series was a British–American co-production involving the BBC's drama production house BBC Cymru Wales for BBC Worldwide and the U.S. premium network Starz. It was broadcast in ten episodes beginning on 8 July 2011 (U.S.) and 14 July 2011 (UK).The central plot of Miracle Day is that suddenly no one on Earth can die, which impels increasingly troublesome legislative changes around the world as the global population soars. In addition to a number of new American cast members and guest actors, showrunner Russell T Davies recruited several American television writers to write for Miracle Day, including Jane Espenson, John Shiban and Doris Egan. British writer John Fay also returned to write for the series, under Davies as head writer. Production was partially divided along trans-Atlantic lines, with Kelly Manners producing in the US, and Brian Minchin in the UK. The majority of the filming took place in Los Angeles, California, with two weeks of additional shooting in Wales.Although the series premiered to a high Audience Appreciation Index rating (85, considered "excellent") and solid ratings in the UK, American critics were on the whole less favourable to the series opener. Reviews on both sides of the Atlantic became increasingly mixed as the series went on. Several commentators felt the series would have worked better as a five-episode series, highlighting concerns with inconsistent pacing, dangling plot threads, and a repetitive feel to mid-series episodes.
The series has a 10-episode companion web series entitled Torchwood: Web of Lies, referenced on the Starz website (but not on the BBC One website) related to the series. It can be obtained as an app from the iTunes Store, and the first episode can be obtained for free, or also viewed on Starz's YouTube channel. It is available in its entirety (without its interactive elements) in the series' DVD and Blu-ray releases. The series premiered on BBC America on 14 September 2013.