The devil is in the details.

And it is in Dr. Marlena Evans.

More than 25 years after “Days of Our Lives” went full on “Exorcist” — in one of the most audacious TV milestones of the 1990s and what remains “one of the memorable moments in American pop culture history,” as Entertainment Weekly recently described — Satan has returned for a redo on the long-running daytime serial in an oh-oh arc still unfolding. With better effects. Most of the townsfolk in the fictional Salem still largely in the dark.

It was outrageous then, during a months-long span when the storyline became water cooler — when even audiences who weren’t soap watchers knew that Marlena, the upstanding doctor and serene diva of Salem, was levitating on occasion and turning into a panther on another — and it remains outrageous today. Even in a genre in which anything can happen — one not unused to returns from the dead and larger than large love triangles.

Even more incredible, perhaps? That, in a culture in which older women often seem to disappear from view, it is 73-year-old Deidre Hall — a great-grandmother on the show at this point — who is front burner on a series running five days a week. Who says there are no parts for women after 40? She first joined the drama in 1976, after all — when Gerald Ford was in the White House and ABBA was new! — and she generously rang me up to chat about it all recently.

Diva on line one!

“I think she has grown with American women,” Hall began to muse, explaining how when her character first appeared on “Days,” even with her own career, “women were not in every marketplace, every executive office … Marlena herself has evolved … has more agency.”

The girl who grew up in Florida dreaming of becoming a psychologist — later stumbling into commercials and then acting, initially doing a short-term stint on “The Young and the Restless” — has ironically played a psychiatrist on “Days” for four-plus decades. (This, in addition to a new, fun, five-part spinoff called “Beyond Salem” that has oodles of hype, uniting many old characters in a globe-spanning adventure story involving a jewelry heist.)

“The show moves with the times,” she acquiesced, when pointing out that Marlena now has one grandson, Will, who is out and gay, and another granddaughter who defines herself as “fluid.” When “Days” premiered back in 1965, that would have been impossible. And when the former got married some years back to another legacy character, Sonny — in what was the first male gay wedding in daytime history — Marlena was front and centre.

“How wise for our writers to have Marlena officiate that wedding,” the timeless blond remembered. The show doubling down, in other words, on the multi-generational oomph intrinsic to the long-form narrative of soaps. For all the camptastic things her character has endured — she has plummeted from a 30-storey window (naturally, she survived), been brainwashed once or twice, and was famously even the surrogate for genetically engineered babies Rex and Cassie during a long coma — at its core “Days” is about heart and hearth. A cosmos of characters with intersecting lives.

Fans will accept even the craziest developments if they’re about characters they are long invested in. See: the “devil possession.” “That will clearly be on my headstone: ‘Deidre Hall, Marlena, possession,’” she laughed.

Did she ever have reservations about doing it? The first time, yes, she admitted, particularly as a person of faith, but she felt she was in good hands because then head writer James E. Reilly was a devout Catholic. Ultimately, she saw it as a story about salvation. This second time ’round, she shared, show proprietor Ken Corday — whose parents, Ted and Betty, together created “Days” — sent holy water to the set.

The drama has not always been on camera, however. Some might remember the groundbreaking TV movie the actress made after enduring years of infertility in her own life while two marriages collapsed, then turning to a surrogate, in which Deidre Hall played, well, Deidre Hall. The result — a quixotic ’90s artifact called “Never Say Never: The Deidre Hall Story” — remains something she is proudest of, largely because it wasn’t about two women fighting (the whole Baby M narrative from that era). “I wanted to give women hope, based on my experience,” she said.

Amazingly, the two twin boys she had via surrogate — “they are grown men now” — have never seen that movie. “One day,” Hall promised. Like sands through the hourglass, as the iconic opening for “Days” goes.

In her day job, she is fortunate to still be working alongside Drake Hogestyn, who plays John Black, with whom she forms one of daytime’s bona fide supercouples. Their convoluted romance was binge television before binge television. About which she explained: “We work so differently and it is gold. Drake has to know everything that happens, wants to be over-prepared … my brain does not require that as much. I like to be surprised in a scene, discover things …”

And the thing she is discovering right about now, over the phone, from her garden in L.A.? A flying little critter. “A hummingbird is joining me now,” she said, delighted as can be. “It is on my skirt!”

Beats the devil.

How long will she continue on the soap? No plans to retire. Feeling blessed for having endured as a leading lady for as long as she has in a world in which most things have an expiry date — “I never had to audition again. Thank God” — she is philosophical about where Deidre starts and Marlena ends. Except for a couple of breaks from the show, the continuity is the thing: “My phone number hasn’t changed. My dressing room hasn’t changed. My parking lot is the same. Thank God for the fans.”

“Days of Our Lives” airs weekdays at 1 p.m. on Global and NBC. The limited series “Beyond Salem” streams in Canada on StackTV and also will have a one-day marathon on the W Network on Oct. 11 starting at 2 p.m.

Shinan Govani is a Toronto-based freelance contributing columnist covering culture and society. Follow him on Twitter: @shinangovani