For the second night running in South Philadelphia, a superstar pop concert began with the sound of Nina Simone's voice.

On Monday, it was "Black Is the Color of My True Love's Hair," setting the mood during Jay-Z and Beyoncè's musical couples therapy session during their On the Run II tour at Lincoln Financial Field.

On Tuesday, it was Radiohead's turn. Before the British art-rockers began the second-to-last date on their summer tour for 2016's A Moon Shaped Pool — they operate on their own timetable — they played a recording of an interview with the jazz and soul singer from 1968.

But Radiohead traffics in dread, not romance, and Simone's words spoke to their chief motif. "I'll tell you what freedom is to me: No fear. I mean, really. No fear."

With that, the fivesome from Oxford, England, fronted by Thom Yorke and Jonny Greenwood — who were scheduled to close out their U.S. trek with a second Wells Fargo show  Wednesday — eased into Moon Shaped's "Daydreaming."

That hypnotic wisp of a song is driven by a repeated piano figure and ends with words presumably directed to the dedicated and faithful Radiohead audience, who were seeing their favorite band in the Philadelphia area for the first time in six years. "We are just happy to serve," Yorke sang unironically, clutching a portable keyboard to his chest. "Just happy to serve you."

The idea of music in particular and art in general as a useful tool in an age of heightened anxiety coursed through the band's 25-song, two-hour-plus set, which was preceded by a worth-getting-there-early-for, trance-inducing set from Junun, the ensemble made up of Israeli composer Shye Ben Tzur, the Indian musical group Rajasthan Express, and Greenwood — who in effect was opening for himself.

Among bands old enough to be in the Rock and Roll Hall of Fame — Radiohead, who released their first single in 1992, should have been inducted this year in their first shot at eligibility — Radiohead is unique in the way its music continues to speak to the now.

That's in part because the band is so creatively restless and their albums have not fallen off in quality precipitously. A Moon Shaped Pool, their ninth, is not their best, but it's not full of songs that send fans scurrying to the bathroom, either.

Thom Yorke of Radiohead performs the at Wells Fargo Center on Tuesday.
CHARLES FOX / Staff Photographer
Thom Yorke of Radiohead performs the at Wells Fargo Center on Tuesday.

But it's also because in both methodology and subject matter, Radiohead's music speaks to the spirit of the always-on-edge digital age. It's twitchy, uneasy, and tech-savvy, employing fractured song structures that are never too tidy and purposeful experimentation that is never merely indulgent. When Greenwood — whose brother Colin plays bass in the band — switches between piano and an electric guitar played with a cello bow in "Pyramid Song," he's not showing off his mad nerd-rock skills —  he's on the hunt for a specific, emotionally impactful sound.

Radiohead arrived at its new millennium identity with its prog-rock meisterwork OK Computer, which came out in 1997 and which received the 20th anniversary deluxe reissue treatment last year, and 2000's Kid A, which premiered the splintered, electronic-textured sonic strategy that pointed the way forward into the new century.

Jonny Greenwood of Radiohead  at the Wells Fargo Center on Tuesday.
CHARLES FOX / Staff Photographer
Jonny Greenwood of Radiohead  at the Wells Fargo Center on Tuesday.

The band — which mixes up its set list from night to night — played songs from throughout their career Tuesday, including from those albums. OK Computer's epic "Paranoid Android" fit into an encore slot and was one of many tunes throughout the evening — "All I Need," from 2007's In Rainbows was another example — that were carried by soaring melodies suitable for singing along with, like the one in "No Surprises," which played like a deceptively gentle resistance anthem as it urged "bring down the government / They don't speak for us."

Those songs underscored the true secret to Radiohead's success. Yes, they're daring, adventurous, dystopian, and, contrary to the "No Surprises" title, actually full of surprises.

But they also make music that's quite often uncommonly pretty and soothing.  The man-bunned and scruffy-bearded Yorke has a gorgeous, floating, unpredictable singing voice and a delivery that is never too on the nose. He's slippery and elusive, mirroring the songs' winding rhythms and melodies, which were largely captivating and which only occasionally drifted aimlessly off into the ether on Tuesday.

The Radiohead live show attracts a gender-balanced crowd considerably younger than the mostly classic rock bands that are capable of filling an arena these days. It's a smartly paced affair, attractively and intelligently presented with a lots of cool lighting and an egg-shaped video screen behind the band showing artfully edited close-ups that create a feeling of sports arena intimacy.

Sweetly delicate strings of songs like the one anchored by the beautifully wrought "Nudes" build to a release of tension in roiling, propulsive numbers that remind you that the group — which also included drummer Philip Selway, guitarist Ed O'Brien, and touring member Clive Deamer as a second drummer — is very much a rock band.

One of those was Kid A's "The National Anthem,"  kicked off by Greenwood knob-twiddling through local radio airwaves and amusingly landing on a  Dietz & Watson deli meats commercial that airs during Phillies broadcasts. When Yorke's ghostly vocal came in, it was to echo the anxiety expressed by Simone in the opening: "Everyone is so near / Everyone has got the fear."

Thom Yorke (left) and Jonny Greenwood of Radiohead at the Wells Fargo Center on Tuesday.
CHARLES FOX / Staff Photographer
Thom Yorke (left) and Jonny Greenwood of Radiohead at the Wells Fargo Center on Tuesday.

After an initial five-song encore, the show closed with a three-song finale that began with Moon Shaped's "Present Tense." Yorke didn't show of any of the herky-jerky moves he'd displayed earlier in the evening that have made him a popular source of material for online GIF makers.

But in the song that vows to "keep it moving … as my world comes crashing down," he did use dance as a metaphor for what Radiohead aims to do to ward off the worry — and the fear — that goes with everyday life. "This dance is like a weapon," Yorke sang as his guitar did a gentle pas de deux with Greenwood's. "Against the present, the present tense."