Torchwood Four
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Torchwood Four was a branch of the Torchwood Institute. The nature of this branch and its personnel was unknown. Bilis Manger's handprint gave him top access at Torchwood Four. (PROSE: The Twilight Streets)
Torchwood Four disappeared. (TV: Everything Changes) The disappearance was caused by the Red Key. (AUDIO: The Torchwood Archive) Agnes Havisham claimed that Torchwood Four's disappearance was a "messy business". (PROSE: Risk Assessment)
Jack Harkness declared "we'll find it some day." (TV: Everything Changes) Suzie Costello had reports documenting her search for Torchwood Four. (PROSE: The Twilight Streets)