Prince Harry's ghostwriter is spilling the royal tea.

J.R. Moehringer got candid about working with the Duke of Sussex on his memoir Spare, which was released earlier this year. And as he noted, it wasn't always smooth sailing, recalling the time he screamed at the prince during a 2 a.m. Zoom call.

"I was exasperated with Prince Harry," J.R. wrote in a The New Yorker essay published May 8. "My head was pounding, my jaw was clenched and I was starting to raise my voice."

At one point during the heated exchange, the 58-year-old thought he may get fired. 

"Some part of me was still able to step outside the situation and think, ‘This is so weird. I'm shouting at Prince Harry,'" J.R. confessed. "Then, as Harry started going back at me, as his cheeks flushed and his eyes narrowed, a more pressing thought occurred: ‘Whoa, it could all end right here.'"

As for what caused their argument?

According to J.R., it was over an anecdote where Harry recalls being "captured by pretend terrorists."

"He's hooded, dragged to an underground bunker," the Tender Bar author explained, "beaten, frozen, starved, stripped, forced into excruciating stress positions by captors wearing black balaclavas."

In his memoir, the Harry & Meghan star wrote that his kidnappers threw him against a wall, proceeded to chock him and and throw insults—including a dig at his late mother, Princess Diana. Harry wanted to include what he said back to his attackers, but J.R. wasn't convinced it was right to add to Spare—becoming a point of contention as they worked on the memoir.

"Harry always wanted to end this scene with a thing he said to his captors, a comeback that struck me as unnecessary," the Pulitzer Prize winner wrote, "and somewhat inane."

On their tense Zoom call, Harry took the opportunity to advocate once again for why it was important to add how the kidnapping ended in his memoir.

"He exhaled and calmly explained that, all his life, people had belittled his intellectual capabilities," J.R. said, "and this flash of cleverness proved that, even after being kicked and punched and deprived of sleep and food, he had his wits about him."

But nonetheless, the novelist stood his ground with Harry eventually conceding and telling him, "‘I really enjoy getting you worked up like that.'"

Aside from their disagreements, working with Harry was a positive experience for J.R., who even spent time at Harry and wife Meghan Markle's Montecito, Calif., home while working on Spare. In fact, he revealed that while staying in their guest house, Meghan would visit with her and Harry's four-year-old son Archie. (The couple also share daughter Lilibet, 23 months). 

And Harry and J.R.'s efforts had an impact on the royal, who even paid tribute to the writer during his book party. 

"He mentioned my advice, to ‘trust the book,' and said he was glad that he did, because it felt incredible to have the truth out there, to feel—his voice caught—‘free,'" the journalist wrote. "There were tears in his eyes. Mine, too."