The Doctor winds up on a far off planet inhabited by pony-like creatures. The planet seems peaceful enough, but strange things keep appearing and disappearing, and he decides to take a deeper look into this subject. Things don't go entirely as planned, though, when he comes across someone very familiar.

When your life is as dull a gray as the world that surrounds you, the mundanities can make it all seem meaningless. Sometimes all we need is a little color -- or six -- to reintroduce us to what truly makes life worth living.

*6-16-2017 Edit, added Rainbow Dash tag because it triggered knighty.*