"Welcome to one of the great unsung currents of American pop music: the forgotten musical mash-up of Latin and Jewish, bagels and bongos, Spanish and Yiddish, manteca and schmaltz, that's been a bubbling undercurrent of American pop music since the early 1900s. It's a story full of Jewish mambo dancers, Jewish salsa greats, beloved sidemen, and record label chiefs on the one hand, and Latino bandleaders, singers, composers, and entrepreneurs on the...