Robert F. Kennedy’s granddaughter reportedly died of an apparent drug overdose at the family’s Cape Cod compound on Thursday — the latest in a long line of tragedies to rock the storied family.

Saoirse Kennedy Hill, 22, was staying at the sprawling Hyannis Port, Mass., home of her grandmother, 91-year-old Ethel Kennedy, RFK’s widow.

By the time medics arrived at the Marchant Avenue mansion at about 2:30 p.m., the young Kennedy was already in cardiac arrest, the Hyannis News reported.

She was rushed to Cape Cod Hospital, where she was pronounced dead. The New York Times said the suspected cause was an overdose, but an investigation by Barnstable police is ongoing.

The death jolted a family long haunted by tragedy.

“Our hearts are shattered by the loss of our beloved Saoirse,” the family said in a statement.

“Her life was filled with hope, promise and love. She lit up our lives with her love, her peals of laughter and her generous spirit. We will love her and will miss her forever.”

The statement said Saoirse was involved with human rights and women’s empowerment causes. She also volunteered to help build schools in Mexico, her family noted.

Ethel Kennedy was quoted in the statement as saying, “The world is a little less beautiful today.” It’s unclear if she was home at the time.

The family statement made no mention of a possible cause of death.

Saoirse was a student at Boston College, where she studied mass media and communications.

Before college, she attended the Deerfield Academy, where she wrote for the school newspaper about her struggle with mental illness.

In a Feb. 3, 2016, article, she wrote, “My depression took root in the beginning of my middle-school years and will be with me for the rest of my life.”

Saoirse was the daughter of Courtney Kennedy Hill, the fifth of Ethel and Robert’s 11 children.

Her father, Paul Michael Hill, is one of the Guildford Four, who were falsely accused of involvement in Irish Republican Army bombings.

Her death is the latest in a series of untimely family fatalities.

Saoirse’s New York senator grandfather, like his brother, President John F. Kennedy, was fatally shot by an assassin, in 1968.

Her uncle David Kennedy died of a cocaine overdose in a Palm Beach, Fla., hotel room in 1984.

Another uncle, Michael, was killed in 1997 when he accidentally skied into a tree.

JFK’s son, John F. Kennedy Jr., died in 1999 when his plane crashed into the Atlantic Ocean off the coast of Martha’s Vineyard. His wife and sister-in-law were also on board and died.

Fifty years ago, Sen. Ted Kennedy’s car plunged off a bridge on Martha’s Vineyard, and his 28-year-old passenger, Mary Jo Kopechne, died.