When Prince Harry picked up the phone in late March and heard the strain in his father’s voice, he immediately knew something was wrong.

It was bad news indeed: Harry was shocked to learn that 71-year-old Prince Charles had tested positive for the potentially deadly coronavirus.

Worse, having just moved to Los Angeles, Harry was 5,000 miles away from his family.

“It hit home for him that Charles and the Queen aren’t going to be around forever,” says a source in the new book “Royals At War: The Inside Story of Harry and Meghan’s Shocking Split With the House of Windsor” by Andy Tillett and Dylan Howard (Skyhorse Publishing), out Tuesday.

“Harry’s biggest fear is not being there if his grandmother were to die,” adds a source in the book.

The worrying update that his beloved dad was sick with COVID-19 was one of many stark reminders that the 35-year-old was stranded a long way from home after quitting Britain with his wife, Meghan Markle, and their 1-year-old son, Archie.

Such struggles in Harry’s new life — first on Vancouver Island, Canada, and now in LA — are laid bare in the new book, along with Meghan’s determination to get what she wants.

“Meghan has always been fascinated with the creation of a ‘brand,'” a former friend tells the authors. “I do not believe she married Harry with that solely in mind, but it was a determining factor.”

Then the question is, how does someone who, as the book says, was born into fame and came to loathe it and someone who aspired to fame and came to weaponize it, live happily ever after in La La Land?

“She’s assuring [Harry] that once things go back to normal, he’ll love their new life in LA,” says an insider. “Meghan wants to take him hiking and talks about the local polo club and how much he’ll love surfing.”

But right now, life is a bit of a glossy facade. The authors paint a depressing picture of the once-adored second son of the late Princess Diana being “overwhelmed with guilt over not being closer to home while this [the pandemic] is going on.”

It seems a heavy price to pay for what many believe was an ill-conceived, somewhat headstrong decision by Harry and Meghan to turn their backs on royal duty, citing their desire to live like a normal family with Archie, far from the media spotlight and stuffy palace protocol.

The duo announced their determination to break from the blue-blooded household in January, just 20 months after their fairytale wedding at Windsor Castle in May 2018. According to sources, the departure — which became widely known as “Megxit” — deeply “saddened” the 94-year-old Queen Elizabeth II.

It also widened the rift between Harry and his once-close brother, Prince William, as well as William’s wife, Kate Middleton. According to a royal insider quoted in the book, the second-in-line to the British throne and his spouse “feel screwed over,” because they will likely have double the workload now that Harry and Meghan won’t be attending many official engagements.

“They think it’s unfair that Harry and Meghan still get to reap the rewards of being part of the royal family without having to put in any effort,” explains the royal insider. (While Harry remains a prince by birthright, he will no longer use that title, or His Royal Highness.)

The royal insider says that Kate in particular is “panicking” over how she’ll “juggle the extra responsibilities with family life” during the pandemic. It’s a time when older royals — like her mother-in-law Camilla Parker Bowles, and father-in-law Charles, who has since recovered from COVID-19 — need to take a break from the front line for their own health and safety.

Image has always been important to Meghan Markle. It’s now more important … [because] she needs income.

 - Source in “Royals at War”

Another person familiar with the situation claims Will and Kate, the Duke and Duchess of Cambridge, sense that Meghan, 38, is a master manipulator of her husband — who is known in inner circles as not being the smartest of men who frequently acts first and thinks later.

“They think it’s pathetic how Meghan works Harry like her own personal puppet,” says a source. “They’ve resigned themselves to losing the Harry they once knew for the foreseeable future.”

According to Ninaki Priddy, who grew up with Meghan, the actress has long known how to shape people and situations to her satisfaction. Priddy reveals in the book how Meghan changed once she landed “Suits,” the USA Network series that brought the first real taste of the stardom she craved.

“There’s Meghan Before Fame and Meghan After Fame … The tone of her voice, her mannerisms, the way she laughed — didn’t seem real to me anymore,” Priddy says. “By Season Two of ‘Suits’ she was turning down lunch with [old friends] because she said she’d be recognized.”

Initially, it looked as if Canada was going to a permanent home for Harry, Meghan and baby Archie, with the family holing up at secluded Mille Fleurs, a French country-inspired five-bedroom house borrowed from an unnamed billionaire on Vancouver Island.

But itchy feet soon struck again. According to the authors, the duchess soon “unleashed her long-desired plan” to move back to Los Angeles, the city where she grew up. It’s also home to her mother, yoga instructor Doria Ragland.

Southern California was calling the ex-actress’s name. After looking at mansions in gated communities around Bel Air, the family moved into an $18 million eight-bedroom Tuscan-style villa on 23 acres of land in Beverly Hills. It is owned by actor and producer Tyler Perry, whom Meghan is believed to have met through their mutual friend Oprah Winfrey.

In Beverly Hills, Meghan is pandering to Harry’s whims, aware his homesickness is likely exacerbated because of the lockdown. She is anxious for the city to reopen so they can start getting out and about again.

Harry — who has taken up yoga to relieve his anxiety — is trying to play down the extent of the discontent he is feeling. At least to his wife.

Comments another of the book’s sources: “Like any household, right now, there are up and downs. To Harry’s credit, he has tried to shield Meghan from his stress. So he’ll confide to friends in London over the phone.”

Los Angeles’ pandemic lockdown did nothing to help matters.

“On top of it all, he’s got cabin fever,” adds that source. “It was far from an ideal situation. Harry’s gone from feeling excited about the move to feeling secretly tortured.”

But the couple is already busy networking in the Golden State and exploring career opportunities for when the pandemic is over.

“They are in touch with a number of LA power players and are looking forward to hosting dinner parties with the likes of George and Amal Clooney and big-time movie producer Jeffrey Katzenberg,” says another insider.

Meghan, who recently did a highly-publicized voice-over for the Disney documentary film “Elephants,” loves the idea of being the breadwinner with Harry as a stay-at-home dad.

“Image has always been everything to Meghan Markle,” a friend of hers is quoted in the book as saying. “It’s now more important for her than ever before because with the Queen’s money no longer pouring in, she needs income.”

But she has no plans to do another TV show like “Suits.” Instead, according to another insider, her husband has been encouraging her to do more voice-over work as well as “writing, producing, and directing in her free time.”

Harry, too, has Hollywood ambitions, focused on documentaries about the charities he supports.

“We’ll see him on camera, mostly as a spokesperson,” a source tells the authors. “He’s not trying to be the next Brad Pitt or anything. He understands it’s a risky venture. Harry knows Hollywood is fickle.

“He wants to get everything right from the beginning and if it all goes well, he’ll use the exposure to shine a light on worthy causes. With Harry and Meghan, it’s not just about making a fast buck — there has to be purpose behind their work.”

Meanwhile, Meghan is enjoying the little things that her renewed life in America can deliver. That includes having the freedom to wear what she wants rather than following strict guidelines from purists at her former office at Kensington Palace.

The book quotes someone on her fashion team as saying that “Meghan was told she needed to start dressing less like a Hollywood star and more like a royal” — like not wearing so much black, and wearing a hat only when the queen approved.

She can also go back to other old Hollywood habits.

The book mentions how Meghan’s “particular brand of up and at ’em West Coast energy” — meaning, she would get up at 5 a.m. and bombard aides with texts — riled her former staff in London and earned her the nickname “Hurricane Meghan.” It also, a source says in the book, led to Kate telling Meghan to not speak to her staff that way.

No matter how Los Angeles changes Meghan — or lets her revert to familiar behaviors, only now with a whole other level of fame — one thing seems to be sure. The authors are convinced Harry will be in Meghan’s thrall for years to come.

As the book puts it: “She is his one survival strategy for his greatest dream — a life forever free of being a royal.”