Torchwood is a British science fiction television programme created by Russell T Davies. A spin-off of the 2005 revival of Doctor Who, it aired from 2006 to 2011. The show shifted its broadcast channel each series to reflect its growing audience, moving from BBC Three to BBC Two to BBC One, and acquiring American financing in its fourth series when it became a co-production of BBC One and Starz. Torchwood is aimed at adults and older teenagers, in contrast to Doctor Who's target audience of both adults and children. As well as science fiction, the show explores a number of themes, including existentialism, LGBTQ+ sexuality, and human corruptibility.

Cardiff is the capital and largest city of Wales. Cardiff had a population of 362,310 in 2021 and forms a principal area officially known as the City and County of Cardiff. The city is the eleventh largest in the United Kingdom. Located in the southeast of Wales and in the Cardiff Capital Region, Cardiff is the county town of the historic county of Glamorgan and in 1974–1996 of South Glamorgan. It belongs to the Eurocities network of the largest European cities. A small town until the early 19th century, its prominence as a port for coal when mining began in the region helped its expansion. In 1905, it was ranked as a city and in 1955 proclaimed capital of Wales. Cardiff Built-up Area covers a larger area outside the county boundary, including the towns of Dinas Powys and Penarth.