The story is talking about the black death's journey .
First of all , the plague started between China and India in March 1349 in east .
The flea live in mouse to feed in it and it go inside the lungs and spread bacteria because the flea loves warm and wet place then the mouse die .
The plague started in east then it went to west
The mouses live in the people house so when the mouse die the flea need to find a new habitat so they go to the people body and live in it . When the disease spread in the human body the flea go to the lungs and fill it with bacteria so the human will struggle an will have a pain death .