I actually began watching the episode half a day ago but decided to stop and go to sleep about halfway through it, which likely says something about the episode’s ability to keep me riveted to my seat despite how much anticipation I had to see the continuation of Benedict Cumberbatch and Martin Freeman’s take on the famous detective duo. Let me therefore say up front that the episode has left me somewhat lost and confused.
The central plot to the movie involves a Mars outpost crew already psychologically fraying after six long and seemingly fruitless months on the Red Planet suddenly discovering alien bacterial life on the day before their replacement crew and ride home to Earth arrives. A mishap occurs and a member of the crew dies but, being exposed to the alien bacteria, is soon reanimated into a zombie-like creature
who that goes about attacking the rest of them.