nine made for this series no  longer exist. Season 1 is almost complete with only one episode  missing (Ticket to Terror), whilst Season 2 is almost completely  missing with only two episodes surviving (Black Echo and A Sinister  Sort of Service). In 2003, D for Destruction, the Season 1 finale  episode, was recovered from the BBC in a mislabeled film can. It was  previously an episode thought not to exist.