In a new documentary premiering in the UK, Syrian activist Wafa Mustafa revisits her ten-year search for her father, Ali Mustafa, who was forcibly disappeared from Damascus in 2013. The film becomes both a personal chronicle and a testament to the thousands of Syrian families still waiting for answers — and for justice. As The Guardian recounts, Wafa’s earliest memories of her father are steeped in music. He played Umm Kulthum constantly, singin…