Since 1907, one Rockport family have continued to make their timeless soda pop the old-fashioned way. Twin Lights Soda-or tonic, as it's still known locally-was started by second-generation Portuguese immigrants in the back of a small-town family grocer and named after the iconic pair of lighthouses just off the coast of Cape Ann. The bottling industry was one of America's great entrepreneurial endeavors, and at its peak. Twin Lights outsold even the two largest national cola brands in the region. But today, while soft drinks are a $45 billion industry, few independents remain. Authors Paul St. Germain and Dev Sherlock trace the fascinating story of one of the last family bottlers still in operation.