Witch 1

A witch house in middle of a village is burned accidentally or otherwise, witch's son dies in that and no one helps. She takes a vow to destroy it.

Detective2

Someone in distress asks for help from a detective and it reaches the culprit and he comes as detective.

Detective

Its starts with a letter written by a distressed woman asking for help from a crime fiction writer. She thinks that the fictional character is alive.
Its based on a real story where Conan Doyle was asked to acquit an alleged criminal.
The writer may have written some replies posing as his fictional character saying that he is busy or something. At last, he had to investigate it all by himself.