A changing cast of Jews, Communists and other endangered individuals spent days or weeks on the upper floors, and if the Gestapo visited, an alarm bell on the second floor allowed Dr. Strobos and her mother to alert the fugitives. They also drilled them in clambering out a window to the roof to reach the relative safety of an adjoining school. Most Jews stayed in the hideout for brief periods until the Dutch resistance could find more reliable sanctuaries.

“We never hid more than four or five at a time,” Dr. Strobos said. “We didn’t have enough food.”

The Gestapo searched the rooming house several times. But Dr. Strobos, a tall, soft-spoken woman, beguiled the Germans with her fluency in their language and her cool, ingenuous pose. Among the Jews she helped hide was a close friend, Tirtsah Van Amerongen; an Orthodox couple with five children who brought their own kosher food; and her fiancé for a time, the particle physicist Abraham Pais.

Dr. Strobos rode her bicycle for miles outside the city to carry ration stamps to Jews hiding on farms. She transported radios to resistance fighters and stashed their guns. She created fake identity cards — ones that were not stamped with a J — either by stealing photographs and fingerprinted documents from legitimate guests at the boarding house or making deals with pickpockets to swipe documents from railway travelers.

She was cold and hungry when she took those risks and was interrogated nine times by the Gestapo. Once, she was left unconscious after an official threw her against a wall.