The Thirteen Problems: A Christmas Tragedy

In an inverted mystery, the murderer is revealed to the reader before the story begins, creating suspense around how the crime was committed rather than who committed it; in 'A Christmas Tragedy,' Miss Marple reveals she knows Mr. Sanders intends to murder his wife from the start, and the suspense comes from watching her attempt to prevent the crime and how he ultimately succeeds through a clever body-switching scheme that exploits the locked hat cabinet and balcony access.