Doctor Who has done murder mystery many times before - most recently in Mummy on the Orient Express - but it never worked quite as well as The Unicorn and the Wasp. Taking elements from Agatha Christies influential work, The Unicorn and the Wasp was camp. Boy was it camp. But it worked. Catherine Tate is on top form in this episode, and is clearly relishing the comedic tones from Gareth Robert's script. There are many memorable scenes, including the Doctor and Donnas infamous kiss, Donna trying to guess the culprit and Donna unwittingly giving Agatha Christie many influences for her future works. Hell, this was an episode all about Donna. Like Partners In Crime, such an episode probably wouldn't have suited a different companion. It is Tates previous work which allows her to excel in this tale; there are tones of many of her sketch show characters in her portrayal here. The Unicorn and the Wasp was, along with Partners In Crime, the only lighthearted episodes in series four and yet the fourth series is generally regarded as the best series of Doctor Who's return. It's all down to Tennant and Tates insatiable chemistry.
