This is quite an unsettling episode that really dives into themes of what happens after death, and why you should never bring the dead back to the land of the living. It's essentially a sequel to the Series 1 episode They Keep Killing Suzie, as well as directly following on from the previous episode 'Reset'.

There's some very chilling stuff concerning the legend of the Grim Reaper, which kind of reminded me a bit of what the Doctor Who two parter The Impossible Planet/The Satan Pit did with the devil. I really like how it leaves so much ambiguous about what this Whoniverse version of death is, again a bit like the devil in The Impossible Planet/The Satan Pit, and showing us the second resurrection gauntlet of the pair after seeing the first in the previous series is and establishing that it operates somewhat differently to the one we saw before is such a great idea.

In fact, the whole thing with the second resurrection gauntlet is brilliant, from that creepy scene with the hand scurrying on the floor to what it does in ageing Martha.