Where is the Black Death most likely to be found in body?

There isn't a disease called Black Death. There was a historical pandemic called Black Death in the Middle Ages which was caused by flea bites infected with Yersinia pestis bacteria, which causes plague. The plague typically affects the lymph nodes, causing painful swellings called buboes. In severe cases, the bacteria can spread to the bloodstream, causing septicemic plague, or to the lungs, causing pneumonic plague.