Mia Schem had been held hostage in Gaza for three days when, she said, she underwent surgery for a gunshot wound she sustained in Hamas’s attack on Israel. For days afterward — forced to share a room with her captor — she received no painkillers and had to replace her own bandages.

The account by Ms. Schem, who has talked about her 55 days in captivity with two television stations and in a photo essay published in the newspaper Yediot Ahronot, has touched a particular nerve in Israel.

It echoes those of other hostages: a lack of food and water and minimal access to medical care. But her interviews and written account, which could not be independently confirmed, have offered the most detailed look at what life was like in captivity. Her family did not agree to an interview with The New York Times.

Ms. Schem, a 21-year-old Israeli French citizen from Shoham, Israel, was kidnapped by Hamas after fleeing the Nova music festival during the Oct. 7 terrorist attack that killed about 1,200 people in southern Israel. Early in the war, the group released a video of her in captivity, the first on any of the more than 230 hostages.

In her recollections since her release, Ms. Schem has described being held in a family’s home in Gaza in a room with her captor, and with his wife and children in the adjacent room. Her only time alone was in the bathroom, where she would occasionally stick her tattooed fingers out of the window in the hopes of being recognized, she wrote in Yediot Ahronot.

One day, as Ms. Schem struggled with a knot in her hair, her captor approached with scissors, she wrote. She screamed at him, telling him she would sort it out herself, which ended up taking her almost two weeks because of her injured arm, she said.

Ms. Schem told Israeli television that some days, her captor’s wife “would bring him food,” without bringing any for Ms. Schem.

“There were days when she wouldn’t let me eat,” Ms. Schem said.

She told Israeli television that at one point her captor called her over to watch footage on television of her mother speaking at a news conference, saying he did so “to hurt me,” but that she nevertheless drew strength from seeing her mother.

Another day, her captor was upset after his friends were killed in an Israeli bombing, she said, adding that she consoled him only in order “to play the game.” Other times, the bombing was close by.

“The windows broke in the home I was in,” she said.

In the last few days before her release, Ms. Schem said, she was taken to tunnels nearly 200 feet below the ground where it was hard to breathe.

In her hostage video released by Hamas, Ms. Schem pleaded to go home and described undergoing surgery. She told Israeli television that she had been instructed to say that she was being cared for.

“You do what you’re told,” she said in describing the video. “You’re afraid to die.”

Ms. Schem was ultimately released in late November during a brief truce between Israel and Hamas. Since then, she said, she has undergone more surgeries because her bone had been heavily damaged when she was shot.

Now at home, she has struggled to cope with her experience in Gaza and with leaving other hostages behind.

“I can’t get it out of my head,” she told Israeli television.