For a moviegoer with a long memory, watching Aubrey Plaza is a little like seeing Winona Ryder or Christina Ricci in their first few films. The same charismatic black cloud follows all three around — a refusal to engage not just with the other people on the screen but the expectations of filmed entertainment itself. They’re just not having any, yet behind the masks of deadpan ennui we sense hearts and sensibilities waiting to explode, in their own time and on their own terms.

Which kind of makes “Safety Not Guaranteed” Plaza’s “Heathers” or “The Opposite of Sex” — the moment when a dour young actress blooms into a darkly radiant star. It’s a tiny movie, a time-travel comedy so strapped for cash it takes place completely in the present, but because it’s so small, you can pinpoint the exact scene when Plaza arrives.