Fear Factors

I was fascinated to discover recently that each October, my friend Alex undertakes a spooky-season film festival, endeavoring to watch one horror flick for each day of the month.I do not expect that his roster includes the 2012 documentary “Part of Me,” a chronicle of the musician Katy Perry’s California Dreams concert tour.

But I happened to watch that film this week, and it made me contemplate what, exactly, makes a movie frightening.“Part of Me” is not a scary movie, not outwardly at least.It’s mostly a confection, lots of footage of Perry dressed up in candy-themed costumes, dancing and singing and gamely greeting her devoted fans in arenas around the world.

There is one scene, however, that comes near the end of the movie.Perry is in São Paulo, Brazil, where the largest crowd of the tour has gathered to see her perform.

As fans fill the arena, we see Perry sprawled backstage sobbing.Her entourage mills about, fretting over how to handle the situation.

“You have two options.You can cancel the show, or you can do your best,” her manager tells her gently.

Perry thinks for a moment, then commands her makeup artist to begin his ministrations.She goes onstage and puts on the spectacle, even though she’s hanging on by a thread.

(The film implies that this episode was, at least in part, precipitated by the breakdown of her marriage to the comedian Russell Brand.)The scene of Perry crying wasn’t outright terrifying in the way a horror movie is, but it filled me with anxiety all the same.Here’s a person laid low with sadness who has to scrounge up some will to go out onstage and be a convincing avatar for uncomplicated joy and delight.

This “show must go on” gumption is the stuff from which stories of cinematic uplift are made, but maybe it was my frame of mind, or the cultural moment, that made Perry’s resilience seem chilling.I admired her fortitude, and felt grateful that I didn’t have a multimillion-dollar machine depending on m...