After her uncle's death, Hepburn, Ella and Miesje left Arnhem to live with her grandfather, Baron Aarnoud van Heemstra, in nearby Velp. Around that time Hepburn performed silent dance performances to raise money for the Dutch resistance effort. It was long believed that she participated in the Dutch resistance itself, but in 2016 the Airborne Museum 'Hartenstein' reported that after extensive research it had not found any evidence of such activities. However, a 2019 book by author Robert Matzen provided evidence that she had supported the resistance by giving "underground concerts" to raise money, delivering the underground newspaper, and taking messages and food to downed Allied flyers hiding in the woodlands north of Velp. She also volunteered at a hospital that was the centre of resistance activities in Velp, and her family temporarily hid a paratrooper in their home during the Battle of Arnhem. In addition to other traumatic events, she witnessed the transportation of Dutch Jews to concentration camps, later stating that "more than once I was at the station seeing trainloads of Jews being transported, seeing all these faces over the top of the wagon. I remember, very sharply, one little boy standing with his parents on the platform, very pale, very blond, wearing a coat that was much too big for him, and he stepped on the train. I was a child observing a child."