“Folie à Deux” does neither. Taking a cue from the last scene of “Joker” — a psych evaluation where Arthur hears Frank Sinatra’s “That’s Life” in his head and starts to sing along — the film is basically one long drawn-out courtroom drama, interrupted by musical numbers (old standards, most of them sung in Arthur’s head).

Folie à Deux never shows us this TV movie, perhaps because that would be funny and interesting, two qualities the film abhors. But it got me thinking.

Instead of stigmatizing mental illness, "Joker: Folie à Deux" becomes a meditation on what mental illnesses can reveal about our societies.