Mars, 2059. Bowie Base One. Last recorded message: ‘Don’t drink the water. Not one drop.’.
The story is set on Mars in the year 2059 where the Doctor encounters the first human colony, Bowie Base One. This is commanded by Captain Adelaide Brooke who turns out to be a pivotal character in the history of humanity. The Doctor must decide whether to use his knowledge of her fate to change history. According to Doctor Who writer and producer Russell T. Davies, the special is closely linked to the next two episodes but is not the first part of a three-part story. The special was dedicated to Barry Letts, the former writer and producer of Doctor Who who died in October 2009.