Having fixed a massive temporal mixup, Jo, Panda and the Prof take a break in the Silurian Era to relax.

But Panda's ill, so they are forced to return to the present day and Panda's alternate Earth to deal with the next unwanted result of the mixup - a lost Earth astronaut!

After confusing him thoroughly, Panda reveals two devastating secrets - and Jo meets a mystery woman on the castle walls...