This one is an art episode, but also a murder episode and also a madness episode. Artist Richard Dadd's life story is quite sad, but his art remained consistently good, even at the lowest points in his life.
Research:

SYMHC Classics: COINTELPRO 1
39:12

Behind the Scenes Minis: It's Not Unprecedented
16:46

The Rendition of Anthony Burns, Part 2
43:32