IT was one of the most shocking news stories of the year. In the summer of 2012, a woman was found dead in the London townhouse she shared with her husband, Hans K Rausing, the son of Tetrapak heir Hans Rausing.

Hans and Eva, an expat American who was born in Hong Kong and raised in England, had struggled with addiction for years, often under the glare of tabloid headlines. They had met in rehab, fell in love, got married, had four children and then relapsed. The relapse lasted for 12 years. He survived, she did not.

Her body was found in their London home, lying hidden underneath bin bags, and her husband was later charged with delaying burial of her body. He pleaded guilty and was given two short suspended prison sentences and a two-year rehabilitation programme.

Now Sigrid Rausing, the sister of Hans, has written Mayhem, a memoir about the impact of addiction on a family. The editor of Granta magazine and the publisher of Granta Books, Sigrid, 55, who lives on a farm in Sussex and in London with her husband Eric Abraham, the film and theatre producer, asks the difficult questions those close to the world of addiction must face.

“Who can help the addict, consumed by a shaming hunger, a need beyond control? There is no medicine: the drugs are the medicine,” she writes. “And who can help their families, so implicated in the self-destruction of the addict? Who can help when the very notion of ‘help’ becomes synonymous with an exercise of power; a familial police state; an end to freedom, in the addict’s mind?”

She has written the book because she “wants to understand how it all began, long before the relapse”. It’s “a story about witnessing addiction”, she writes, adding, “Addiction stories are the same the world over… in our case, what made the story different was partly the fact that it became so public. Witnessing the apparently voluntary physical and mental decline of people you love is inexpressibly painful.But you don’t want the media to own the story of your life.”

In Mayhem, she writes that Hans and Eva’s addiction “was the worst thing that had ever happened to us”, dragging the family down into the “underworld of mute slow-motion grief”.

Her description of the family’s suffering is made all the more poignant by her vivid descriptions of their childhood and particularly her brother before addiction: “My brother: straggly brown hair, green eyes, sooty eyelashes. A touch of something different about him; I’m not sure what. A bit unkempt, perhaps – but this was the 60s and 70s after all.”

In the early 1980s, Hans travelled with friends through the Soviet Union, China and India. It was when they went to Goa that they met some Italian women staying on the beach. “That was his introduction to heroin,” Sigrid writes.

His addiction ebbed and flowed, in and out of rehab, and as he got better after one stint in rehab, Sigrid became depressed, “a palpable presence, possessing me. A cold claw held me by the throat… held me captive”. She concluded that Hans was imprisoned by by addiction and that she was just as imprisoned by it.

For 11 years Hans and Eva managed to kick their habits and became society figures. It was a glass of champagne on New Year’s Eve in 1999 that kickstarted their addictions. By 2007, social workers had become involved with Hans and Eva and their children, and then the children came to live with Sigrid and Eric. “Hans and Eva loved their children; I know that,” writes Sigrid, who has dedicated her book to the four children. “But isn’t that also a cliche of parenting? What’s the point of love if drugs come first?”

The story culminates in the squalid death of Eva in that summer of 2012, leaving Sigrid, a billionaire philanthropist and the author of two previous books, trying to make sense of what happened to her brother and his wife. As the American novelist Siri Hustvedt describes it, Mayhem “is a fierce, lyrical and lucid memoir that asks agonising questions about guilt, innocence, and judgment and reminds us how difficult it can be to untangle one from the other.”

Mayhem: A Memoir by Sigrid Rausing, is published this month (September) by Hamish Hamilton, priced £16.99.

Picture of Sigrid Rausing: Tom Rausing.