Sometimes backstories are as entertaining as the songs themselves.

With classic rock playing in the background, I was putzing about the kitchen when the famous opening riff to the Rolling Stones’ “Gimme Shelter” from 1969 rose from Alexa, Amazon’s magic little music machine. It jolted me into the past. Of course, I cranked it up in tribute.

As the music reached its crescendo, I wondered, for the first time since the song was released 50 years ago, about the remarkable background singer belting out that iconic, scorching, gospel-tinged vocal behind Mick Jagger. Her performance was as much a symbol of the sixties as anything else.

I discovered she is a talented, gutsy survivor.

“Gimme Shelter” is the apocalyptic anthem of the 1960s, its foreboding lyrics reflecting dark tension: “Ooh, see the fire is sweepin’, our very street today,” “War, children, it’s just a shot away,” and “Rape, murder, it’s just a shot away.”

Newsweek described the song as “ecstatic, ironic, all-powerful, an erotic exorcism for a doomed decade.”

The song first came to Keith Richards as he sat looking out the window of an apartment in London, exploring the opening riff on his guitar. It was a dark, stormy day, a monsoon, and Richards watched “all these people with their umbrellas being blown out of their grasp and running like hell. My thought was storms on other people’s minds, not mine.”

The young woman who lit up the refrain with her fiery delivery is Merry Clayton.

Born on Christmas Day (hence, “Merry”) in New Orleans, she was the daughter of a baptist minister, who raised her on the Bible and gospel music. She sang in the church choir.

The family moved to Los Angeles when Clayton was young, where she began her recording career in 1962 at the age of 14, singing a duet with Bobby Darin. She became one of Ray Charles’ Raelettes in the sixties, and studio producers knew her voice well.

Finishing up their album “Let It Bleed,” The Rolling Stones were in an L.A. studio working on “Gimme Shelter” when they decided they needed a female voice. Producer Jack Nitzsche called his friend Merry Clayton.

Clayton was just 20 years old, married, and very pregnant when she sleepily rolled over and picked up the phone.

She reluctantly agreed to help, but due to the late hour, she wasn’t about to change her clothes.

In an NPR interview years later, Clayton said: “I’m wearing these beautiful pink pajamas, my hair was up in rollers. But I took this Chanel scarf, wrapped it round the rollers so it looked really cute, went to the bathroom and put on a little lip blush — ‘cos there’s no way I’m going to the studio other than beautiful!” She threw a fur coat over her night clothes.

Clayton arrived at the studio, where she met Keith Richards and Mick Jagger for the first time (in her curlers and pajamas!).

Jagger handed her the odd lyrics. She later recalled: “I’m like, ‘Rape, murder…’? You sure that’s what you want me to sing, honey? He’s just laughing, him and Keith.”

She banged the song out in three takes. “So it was three times I did it, and then I was gone. The next thing I know, that’s history.”

The song’s darkness continued when, upon returning home, Clayton suffered a miscarriage and lost her baby. Some think it was the punishing performance she provided in the studio.

A Grammy nominee, she went on to record and perform with every major music star in following decades: Barbara Streisand, Linda Ronstadt, Carole King, Michael Jackson, Aretha Franklin, Diana Ross, and so many others.

“Gimme Shelter” became the title track of her debut solo album, released in 1970. Along with her recording career, she became a movie and television actress.

Then, in June 2014, darkness struck again. Clayton was severely injured in a car collision, losing both of her legs at the knees.

“Oh my God, I was at the pinnacle — I was at the top of my game,” she said of her life at the time of the accident. She spent five months in the hospital.

Clayton drew the strength to survive the tragedy from her lifelong faith. Now in her early seventies, she still lives in California.

When she received the Clark & Gwen Terry Award for Courage at the Jazz Foundation of America’s “A Great Night in Harlem” gala at the Apollo Theater in 2015, Keith Richards noted the occasion with a live performance of “Gimme Shelter.”

That courageous, feisty, spiritual woman in her pajamas at midnight pulled the world’s angst from her soul, giving the Stones’ anthem for the violent sixties exactly what it needed. Thank you, Merry Clayton.

Say it with me: “Alexa, play ‘Gimme Shelter!’” Now, crank it up.

John Steward lives in Waterford. He can be reached at tossinglines@gmail.com.