The 5th Doctor, Peri and Erimem arrive on a planet in the midst of snow storm and come across a heavily pregnant woman and her husband struggling to make their way into the nearby town. Once there, they help deliver the baby as well as encourage the locals to rise up against a rather unscrupulous landowner.

It's inoffensive and the TARDIS regulars are well characterised, particular Erimem's penchant for fighting social injustices in the worlds she visits (and this isn't surprising as the author is Erimem's creator Iain McLaughlin).

Peri gets to decorate a power core like it's a Christmas tree and it is revealed that the Doctor has engineered the snow storm and their visit to ensure that the best people are running the colony due to its future importance in a war.

It's Christmassy in that it borrows from the Nativity story, A Christmas Carol and a general feeling of 'making the best of it' and people coming together.