Planet of the Dead was the first of the 2009 specials that ended David Tennant's tenure as the Doctor. It teamed the Tenth Doctor up with an aristocratic thief named Lady Christina De Souza for a one-off adventure that also heavily involved UNIT. Behind the scenes, it was important for a number of innovations, as it was the first episode to be filmed in HD, and the first to involve location filming in the Middle East. As of 2013, it was the only Doctor Who Easter special.