Ekaterina Romanovskaya froze. It was a warm and sunny day in late May 2000, and the 25-year-old interpreter had just dropped her 3-year-old daughter off at kindergarten in their hometown of Volograd, a city in southwestern Russia, when a man she had never seen before appeared behind her. “We need to talk about the little girl,” the stranger said. Romanovskaya glanced over her shoulder.

She didn’t recognize the man, and there was no obvious reason to run, but Romanovskaya sensed something amiss. Without saying a word, she started walking toward her parents’ apartment, her childhood home. It was a route she could walk blindfolded—perhaps she’d lose the unsettling stranger in the crowd.

When she reached the building, Romanovskaya took the stairs rather than the elevator. It was the kind of tiny decision women make a hundred times every day—instinctive, automatic. But today, decades later, Romanovskaya, now 45, says the decision saved her life.

Because when the same strange man who had so unnerved her on the street broke down the building door and cornered Romanovskaya in the stairs with a hunting knife, she had a chance to scream. “The only thing I had to fight for my life was my voice, so I cried out,” Romanovskaya says. “I called for help as loud as I could.”

Then the man turned the knife on her, and the wall beside her turned red.

“A fountain of blood emerged from my neck,” recalls Romanovskaya. “I reached up to stop the blood with my hands, but my body was totally unprotected. He tried to reach my heart with his knife three times, but my bones saved me: my ribs, my collarbone.” By the time a neighbor came into the stairwell and the attacker fled, Romanovskaya had nine critical stab wounds to her neck, chest, and torso.

Her yoga pants were the only thing that had stopped her internal organs from spilling out onto the floor.

Decades after the attack, in 2016, Romanovskaya, along with cofounders Nikita Marshansky and Leonid Bereshchansky, launched Nimb: a “smart ring” designed to act like a panic button and inform friends, family, and law enforcement if the wearer is in danger.

When the man attacked Romanovskaya in 2000, she had no cellphone to call for help. “I asked myself: What if I’d had a gun?” she says. “But I decided that a gun probably would have made the situation worse. I realized that the most important thing is to call for help.”