Pythagoras' Virus

This is the sixth story from Season 23.
==Story==
A 
==Cast==
The Doctor - Alfred EnochLouie Russell - Nico GreethamRuth Hill - Yara Shahidi
===Guest===
* Vicki - Maureen O'Brien (featured in Pythagoras' Virus)
*
==Behind The Scenes==
This episode would see the return of Vicki as played by Maureen O'Brien.