The Watchmakers by Harry Lenga, Scott Lenga

Harry Lenga was born to a family of Chassidic Jews in Kozhnitz, Poland. The proud sons of a watchmaker, Harry and his two brothers, Mailekh and Moishe, studied their father's trade at a young age. Upon the German invasion of Poland, when the Lenga family was upended, Harry and his brothers never anticipated that the tools acquired from their father would be the key to their survival. Under the most devastating conditions imaginable - with death always imminent - fixing watches for the Germans in the ghettos and brutal slave labour camps of occupied Poland and Austria bought their lives over and over again.