“American Horror Story” resuscitated Jessica Lange’s career — but her diva turns in that outlandish show have almost obscured the fine actress she is. Her magnetic performance in “Long Day’s Journey Into Night” comes as a healthy reminder. It’s a treat to watch someone so effortlessly bridge the worlds of Eugene O’Neill and basic-cable frights.

Lange applies a relatively light touch here, which wasn’t a given considering her character, Mary Tyrone, is a morphine addict. Prescribed the drug by a quack decades earlier, she’s tried and failed to shake her addiction, and is now either craving a fix or riding an artificial high.

It doesn’t help that she’s married to a miserly blowhard and has two children who are difficult in different ways — a drunk ne’er-do-well and a sensitive aspiring writer who, like all sensitive aspiring writers, has consumption.

This set-up could easily have resulted in flashy posturing — watch Mary nod off after shooting up! — especially considering who’s also on that stage: Gabriel Byrne as the husband, Michael Shannon and John Gallagher Jr. as the sons.

Instead, the show simmers at a low, but effective, boil. It’s striking to consider how minimal it is — four characters (plus a maid) over a single day on a single set — and how epic it feels, stretching out to nearly four hours of slo-mo family implosion.

It says a lot about O’Neill’s text that even in a staging as pedestrian as this one, time flies — except when Byrne and Gallagher butt heads in an extended confrontation made mundane by the younger actor’s performance. Byrne fares best whenever he’s opposite Lange — we understand how these two were once in love.

Still the stage belongs to Shannon and especially Lange, who slowly builds to Mary’s operatic aria of desperation — few actors can express vulnerability so achingly. You don’t need shock tactics to rivet an audience in its seats.

American Airlines Theatre, through June 26; 225 minutes, one intermission.