In his forthcoming memoir, Prince Harry claims that his brother, Prince William, physically attacked him, the Guardian reports.

Harry makes the claim in Spare, his much-hyped book that is reportedly being met with dread by members of the U.K.’s royal family, who worry that it will paint them in an unflattering light—particularly after last month’s release of Harry & Meghan, a Netflix documentary series about Harry and his American wife, Meghan Markle.

The Guardian managed to obtain a copy of Harry’s book, which is heavily embargoed by its publisher, Random House.

In the memoir, Harry writes that William visited him at his then home, Nottingham Cottage, to discuss “the whole rolling catastrophe” that their relationship had become. William complained that Markle was “difficult” and “rude.”

A shouting match ensued. “Willy, I can’t speak to you when you’re like this,” Harry says he told his brother, giving him a glass of water.”

Then, William “set down the water, called me another name, then came at me. It all happened so fast. So very fast. He grabbed me by the collar, ripping my necklace, and he knocked me to the floor. I landed on the dog’s bowl, which cracked under my back, the pieces cutting into me. I lay there for a moment, dazed, then got to my feet and told him to get out.”

William left, then came back and apologized, telling Harry, “You don’t need to tell Meg about this.”

Spare is scheduled for publication next Tuesday by Random House.

Michael Schaub, a journalist and regular contributor to NPR, lives near Austin, Texas.