Kala travelled in time to 1933 alongside Jode and Fatboy. They were looking for an alien device capable of destroying worlds. After the device was activated, Jode was particularly in favour of using Fatboy's android ability to nuke/sterilise that area, Kala agreeing with the reasoning on the grounds that the explosion would have a limited effect on Earth's history and believed her mere existence proved that it wouldn't affect her future.
The Eighth Doctor convinced her that she had to find another way, and she helped him track down and destroy the device (although he still had to disarm Fatboy when Jode turned him on without Kala's permission). (PROSE: Eater of Wasps)