The High Plenipotentiary of Mundus Canatari was a monarch. Also holding the titles "Wielder of the White Incarnate Ring" and "Speaker to Star-Whales", the High Plenipotentiary had a space station arboretum and ruled for five thousand years.
He was prejudiced against temporary workers, and wore robes the Tenth Doctor thought were worse than those of the Time Lords. He had never worked a day in his life, a fact betrayed by the state of his hands.
To commemorate the five thousandth anniversary of his reign, the High Plenipotentiary threw a party at his arboretum. He sent the Doctor an invitation, as he was part of a set in the universe who saw being the last of the Time Lords as strangely prestigious and sought to get him to their parties. The Doctor usually ignored such invitations, which filled an entire room in the TARDIS, but he and Donna had been put in the mood for a party after their recent adventure with Agatha Christie.
Donna was a former temp who had had various short-lived job positions, and so she and the Doctor had made up several pompous titles to use to give her a grand entrance at the party, including Wielder of the Blessed Photocopier at H.C. Clements and Sacred Acolyte of the Fraternity of West Ham. Things went badly when the High Plenipotentiary asked Donna how long she had held some of those titles. Donna ended up insulting him. In the ensuing chaos, the High Plenipotentiary's security robots were sent after the Doctor and Donna, and the arboretum began venting its atmosphere into space.
The Doctor and Donna argued about how the argument had begun while they escaped the robots, and the Doctor looked for a way to stop the venting before all the air was gone. The Doctor told Donna that she was picking their next destination.
The Doctor did four clever and risky things to the arboretum's systems to save it, while Donna led the Guild of Non-Permanent Staffers in an uprising that toppled the High Plenipotentiary. Affterwards, the Doctor and Donna resumed their argument inside the arboretum, pointing out the state of the High Plenipotentiary's hands and that the Doctor had left her making small talk with a "stuffy old git". After Donna told the Doctor where she wanted to go next, without telling him why, the Doctor agreed that the High Plenipotentiary had been "a bit stuffy", and the two laughed about his robes. (PROSE: Wannabes [+]Loading...["Wannabes (novel)"])