Wells, Carolyn: The Crime in the Crypt (1928), v1; 6 Aug 2019
 

A tour guide leading a group of American tourists in Britain accidentally discovers a brand new dead body in an ancient sarcophagus beneath a cathedral, shot to death. The victim is identified by his possessions as an American tourist, not part of the tour guide's group but from the same ship.

The investigation leads back to the USA, to a dark family secret, and is solved by Fleming Stone