Anne Washburn’s peculiar, grim Mr. Burns deals with collective memory after a nuclear holocaust. It’s also based on “Cape Feare,” the 1993 episode of The Simpsons where the deranged Sideshow Bob tries to kill Bart on a boat, making this show an intentionally messy adaptation of a parody of a remake. Got that? Mr. Burns starts slow but really comes together in the last act, an operatic pastiche in which the more nuclear-themed hits of the twenty-first century (“Toxic”, “Radioactive”) get smooshed together as a Michael Jackson-inspired Bart duels with a sinister, spry nemesis.