What is the main conflict in The Nine Tailors: Changes Rung on an Old Theme in Two Short Touches and Two Full Peals by Dorothy L. Sayers?

After a disfigured corpse is discovered in the graveyard of Fenchurch St. Paul, Lord Peter Wimsey follows various clues to find the identity of the stranger and how he died, and unravel his link to a jewel theft that took place in the village.